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LABORATORY  MANUAL 

OF 

A  YEAR  IN  SCIENCE 

THALMAN  AND  WE  c  KEL 


LABORATORY  MANUAL 

OF 

A  YEAR  IN  SCIENCE 

JOSEPH  L.  THALMAN,  A.M. 

FORMER    HEAD    OF    BIOLOGY    DEPARTMENT,    OAK    PARK    AND    RIVER 

FOREST    TOWNSHIP    HIGH    SCHOOL  ;    PRINCIPAL    OF 

HIGH    SCHOOL,    NEW    CASTLE,    PA. 

AND 

ADA  L.  WECKEL,  M.S. 

HEAD   OF    BIOLOGY    DEPARTMENT,    OAK    PARK    AND    RIVER    FOREST 
TOWNSHIP    HIGH    SCHOOL,    OAK   PARK,    ILLINOIS 


CHICAGO  NEW   YORK 

ROW,  PETERSON  AND  COMPANY 


o 


COPYRIGHT,  1916 
ROW,  PETERSON 
AND  COMPANY 


PREFACE  FOR  THE  LABORATORY  MANUAL 

Laboratory  work  is  an  essential  part  of  any  course  in 
science.  The  mental  development  acquired  by  pupils 
performing  a  series  of  experiments,  interpreting  their 
results,  and  carefully  recording  them,  is  of  equal,  if  not 
more  value,  than  the  mere  accumulation  of  facts.  We 
cannot  justify  the  existence  of  any  course  in  the  high 
school  which  has  the  acquiring  of  information  as  its  only 
purpose.  The  performance  of  experiments  is  not  a 
mechanical  part  of  the  course  in  which  the  use  of  the 
intelligence  of  the  pupil  plays  no  part.  Too  much  em- 
phasis can  not  be  placed  upon  the  fact  that  the  pupil 
must  perform  experiments  intelligently,  using  his  head  as 
well  as  his  hands.  Frequently  beginners  are  inclined  to 
think  that  laboratory  work  is  merely  entertaining. 

The  following  outlines  for  experiments  are  the  result 
of  about  fifteen  years  of  experiment  and  search  for  inter- 
esting and  fundamental  scientific  matter  adapted  to  the 
age  and  preparation  of  pupils  entering  the  high  school. 
During  this  period  of  experimentation  from  six  to  nine- 
teen classes  a  year  have  pursued  this  course.  It  has  thus 
been  tried  on  thousands  of  students  under  the  direction 
of  many  teachers.  We  gratefully  acknowledge  our  indebt- 
edness to  these  teachers  for  their  many  valuable  sugges- 
tions and  criticisms. 


35939 


^  MANUAL 

Since  first  year  pupils  have  had  no  training  in  scientific 
methods,  the  experiments  must  necessarily  be  short  and 
simple.  As  far  as  possible,  the  following  experiments 
should  be  performed  by  the  pupils,  working  individually, 
or,  if  necessary,  in  small  groups.  We  are  convinced  that 
the  training  acquired  by  pupils  in  this  way  is  much 
greater  than  that  obtained  when  the  teacher  demonstrates 
all  of  the  experiments.  With  the  expenditure  of  a  very 
small  amount  of  money,  it  is  possible  to  purchase  the 
apparatus  necessary  for  the  equipment  of  a  laboratory 
for  individual  experimentation. 

Supplementary  or  alternative  exercises  are  frequently 
given.  Since  both  experiments  in  such  cases  develop  or 
illustrate  the  same  principle,  it  is  not  essential  that  both 
be  performed.  Pupils  should  also  be  encouraged  to  devise 
experiments  of  their  own.  If  the  laboratory  sections  are 
very  large,  this  latter  feature  is  impractical. 

During  the  first  part  of  the  course  it  is  advisable  for 
the  teacher  to  read  carefully  the  Directions  with  the 
pupils.  There  are  always  some  members  of  a  class  who 
acquire  with  difficulty  the  ability  to  read,  interpret,  and 
follow  directions  intelligently.  A  note  book  kept  by  each 
pupil  should  contain  records  of  most  of  the  experiments 
performed.  The  record  of  each  experiment  should 
include : 

1.  An  account  of  the  method  used  in  performing  the 
experiment. 

2.  A  simple  diagrammatic  drawing  of  the  apparatus 
used. 


PREFACE  FOR  THE  LABORATORY  MANUAL      5 

3.  A  statement  of  the  results. 

4.  A  conclusion  drawn  from  the  results,  when  a  con- 
clusion is  possible. 

It  is  essential  that  these  notes  are  clearly  and  concisely 
expressed  and  neatly  kept. 

The  development  of  this  laboratory  course  could  not 
have  been  made  possible  except  for  the  encouragement, 
sympathetic  interest,  and  faith  of  Mr.  J.  C.  Hanna,  to 
whom  we  hereby  acknowledge  our  indebtedness. 


CONTENTS 

Exercise  Page 

1.  Does  Gas  Occupy  Space? 15 

2.  Comparison  of  English  and  Metric  Systems.  16 

3.  Does  Gas  Have  Weight? 19 

4.  Diffusion  of  Liquids 21 

5.  Diffusion  of  Liquids  through  a  Membrane . .  22 

6.  Diffusion  of  Gases 25 

7.  Diffusion  of  Gases    (Demonstration) 26 

8.  Mixing  of  Alcohol  and  Water 27 

9.  Effect  of  Heat  on  Solids    28 

10.  Effect  of  Heat  on  Liquids    29 

11.  Effect  of  Heat  on  Gases 31 

12.  Cohesion,  Adhesion,  and  Gravity 32 

13.  Thermometers  34 

14.  Measurement  of  the  Heat  of  a  Flame 35 

15.  Change  from  a  Solid  to  a  Liquid 38 

16.  Solution   39 

17.  Change  from  Liquid  to  Solid 40 

18.  Change  from  a  Liquid  to  a  Gas 41 

19.  Effect  of  Pressure  on  Boiling  Point 42 

20.  How   Water   is   Distilled 43 

21.  Evaporation    44 

22.  Physical   Change 45 

23.  Chemical  Change 46 

24.  Mechanical  Mixture 47 

25.  Chemical  Synthesis. 48 

26.  Chemical  Analysis ". 49 

27.  Carbon    50 

28.  Phosphorus  (Demonstration) 51 

7 


8  CONTENTS 

Exercise  Page 

29.  Sulphur    .  52 

30.  Iron     , 53 

31.  Oxygen  55 

32.  Hydrogen    57 

33.  Nitrogen 59 

34.  Acids  and  Bases 60 

35.  Salts   and   Neutralization 61 

36.  A  Simple  Electric  Cell 62 

37.  Composition  of  Water  (Demonstration) ....  63 

38.  Composition  of  Air 64 

39.  Does  Air  Exert  Pressure?  (Demonstration) .  66 

40.  Barometer    (Demonstration) 67 

41.  Siphon    68 

42.  Convection     69 

43.  Moisture  in  the  Atmosphere — Condensation.  70 

44.  Study  of  the  Weather  Map 71 

45.  Water  Capacity  of  Soils 75 

&.  Soil  Solutions , 76 

47.  Gross  Structure  of  Leaves 77 

48.  Chloroplasts    78 

49.  Making  of  Food  for  Plants 79 

50.  Making  of  Food  for  Plants,  continued 80 

51.  By-Products  in  Food  Making 80 

52.  Transpiration 81 

53.  Rate  of  Transpiration 82 

54.  Is  Air  Necessary? 83 

55.  Exchange  of  Gases  in  Respiration 84 

56.  Roots    85 

57.  Roots  as  Organs  of  Absorption 86 

58.  External  Structure  of  Stems 87 

59.  Internal  Structure  of  Stems 88 

60.  Functions  of  Stems 89 

61.  A  Typical  Flower 90 


CONTENTS  9 

Exercise  Page 

62.  Structure  of  Seeds 91 

63.  Seed  Dispersal 93 

64.  Conditions  for  Germination 93 

65.  Seedlings 95 

66.  Bacterial  Cultures 97 

67.  Conditions  for  Bacterial  Growth 100 

68.  Root  Tubercles    101 

69.  Tests  for  Foodstuffs 103 

70.  Foodstuffs  in  Common  Foods 104 

71.  Study  of  the  Mouth  (home  study) 105 

72.  Alimentary  Canal  and  Digestive  Glands 

(Demonstration)    107 

73.  Digestion  in  the  Mouth 109 

74.  Digestion  in  the  Stomach 110 

75.  Digestion  in  the  Intestine 112 

76.  Absorption    113 

77.  Study  of  Beef  "Pluck"  (Demonstration)...  114 

78.  Blood    116 

79.  Respiratory  Organs  and  Mechanics  of  Res- 

piration  (Demonstration) 118 

80.  Comparison  of  Expired  and  Inspired  Air. . . .  120 

81.  School    Ventilation 122 

82.  The  Kidneys 123 

83.  The  Skin 124 

84.  The    Skeleton 125 

85.  Structure  and  Composition  of  Bone 127 

86.  Levers     128 

87.  Muscles    (Demonstration) 130 

88.  Nervous  System   (Demonstration) 131 

89.  Cutaneous  Sensations 133 

90.  Organs  of  Taste  and  Smell 134 

91.  Organ  of  Sight 135 

92.  Organ  of  Hearing1 137 


APPARATUS 

The  following  lists  contain  all  the  apparatus  and  sup- 
plies necessary  for  a  satisfactory  presentation  of  the 
laboratory  exercises  given  in  this  manual.  Many  of  the 
most  expensive  pieces  of  apparatus,  marked  with  an 
asterisk  in  the  following  lists,  may  be  eliminated  with- 
out requiring  the  omission  of  many  exercises.  In  many 
cases  it  is  possible  to  substitute  simple  improvised  appa- 
ratus for  these  more  expensive  pieces. 

A  school  equipped  for  laboratory  work  in  physics  and 
chemistry  is  equipped,  also,  for  a  general  science  course. 
The  expense  of  equipping  a  laboratory  for  general  science 
will  be  nominal,  if  the  equipment  in  the  other  labora- 
tories in  the  school  can  be  used. 

The  following  named  apparatus  can  be  obtained  from 
dealers  in  laboratory  supplies.  The  prices  given  here 
are  only  approximate.  Any  school  can  secure  a  discount 
of  from  10  to  25  per  cent  from  these  prices. 

A.     PHYSICAL  APPARATUS 

1.  For  demonstration  work,  one  set  for  the  whole 
class. 

*1  air  pump $10.00  3  animal  membranes.  .  .  .30 

2  balances,  spring 1.00  1  bar  compound 50 

*1  balance  and  weights.  9.08  1  blow  pipe 14 

1  ball  and  ring 1.00  1  brass  globe,  hollow..  2.25 

1  balloon,  rubber 06  2  clamps,  burette 16 

11 


12 


APPARATUS 


1  cotton   roll    

3  deflagrating  spoons.  .  . 

3  dry  cells    

*1  drying  oven  (house- 
hold type  may  be 
used)  

1  pk.  filter  paper 15 

*  1  Magdeburg    hemi- 
sphere   

2  magnets 

2  metric  sticks    

2  mortars  and  pestles.  . 

1  pan,  dissecting 

1  pinch   cock    

The  above  list  does  not  include  several  expensive  pieces 
of  apparatus  wjrich  are  not  used  frequently  enough  to 
justify  placing  them  in  the  list.  They  are :  a  barometer, 
a  compound  microscope,  a  skeleton,  and  an  anatomical 
manikin,  or  models  of  the  principal  organs  of  the  body. 
.  2.  For  individual  work,  one  set  for  each  pupil,  or  for 
each  group  of  pupils. 


.20 

1  porous  cup    . 

.14 

.30 

*1  pneumatic  trough    .  .  . 

.81 

1.05 

1  ring  stand    

1.12 

1   rubber  dam,  1  sq.  ft.. 

.30 

1  shears  

.67 

5.50 

1  ft.  tubing,  rubber,  Ty 

.18 

.15 

1  ft.  tubing,  rubber,  Vs" 

.12 

1  twine    .  .    .  . 

.05 

3.00 

.45 

Total 

$39  73 

.50 

Total        not        essential, 

.40 

marked  with  an  aster- 

.20 

isk  . 

28.39 

.10 

Total,  essential    

11.34 

1  asbestos  sheet,  8  x  8  x 


1  metric  rule 


.03 


,V 


.  .  $0.10       2  needles,  dissecting 12 


1  Bunsen  burner  (alco- 
hol lamp  may  be 
used)  

1  test  tube  clamp 

1  forceps  

1  lever  holder    


22 

.07 
.10 

.18 


1  ring  stand  and  rings.  .        .54 

1  scalpel    25 

1  test  tube  rack 38 

1  wire  gauze  5x5" 05 


Total    $2.04 


B.     GLASSWARE 
1.     Demonstration,  one  set  for  the  whole  class. 

2  battery  jars $1.00 

*1  belljar,  closed  ground  glass  stopper.  .  .  .      1.50 
*1  burette,  100  c.c 1.80 


APPARATUS  13 

1  pk.  corks 35 

^  oz.  round  cover  glasses 30 

fl  crystallizing  dish,   10" 1.00 

2  cylinders,  glass,  3  x  15" 1.66 

fl  electrolysis  apparatus    5.00 

1  graduate,  100  c.c 56 

1  glass  plate,  10" 25 

2  doz.  slides,  microscopic    25 

5  thistle  tubes 40 

1  torricellian   tube    28 

-i  Ib.  glass  tubing,  &  " 22 


Total  $14.57 

Total,  not  essential..  0.30 


Total,  essential  5.27 

2.     Individual,   one  set  for  each  pupil,   or  for  each 
group  of  pupils. 

2  beakers,   230  c.c $0.30 

2  bottles,  wide  mouth,  8  oz 10 

1  evaporating  dish    25 

2  flasks,  16  oz 36 

1  funnel 20 

1  petri  dish,  100  mm.  diam 25 

1  plate,  3" 05 

1  stirring  rod,  glass,  5  x  7V' 02 

1  set  stoppers,  rubber 50 

No.  3,  1-hole  No.  8,  solid 

No.   3,  2-liole  No.  8,   1-hole 

No.  2,   1-hole  No.  8,  2-holo 

12  test  tubes,  6  x  %" 25 

1  test  tube,  hard,  6  x  %" 10 

1  test  tube  brush    1)5 

1  thermometer,  10°  to  210°  C 1.25 

1  tumbler,  glass    04 


Total  .  .   $2.72 


14 


APPARATUS 


C.     CHEMICALS 

The  amount  of  each  chemical  will  vary  with  the  size 
of  the  class,  but  the  total  cost  of  chemicals  will  not 
exceed  $12.00. 

*Acetic  acid 

Alcohol 

Ammonium  hydroxide  (house- 
hold ammonia) 

Charcoal 

Chloroform 
*Cobalt  chloride 

Copper,  sheet 

Copper  sulphate 

Eosin    (red   ink   may   be    sub- 
stituted) 
*Ether 

Fehling's  solution,  No.  1  and 
No.  2 

Flax  seed,  ground 

Hydrochloric  acid 

Iodine 

Iron  filings 

Iron  wool 

Lime  water  (made  by  slack- 
ing lime  in  water  and  filter- 
ing off  water) 

Litmus  paper,  red  and  blue 


Manganese  dioxide 
Marble 
Mercury 

*Mercuric  chloride 
Mercuric  oxide 


Molasses 

Nitric  acid 

Oxalic  acid 

Olive  oil 

Pancreatin 

Paraffin 

Pepsin 

Phosphorus,  red 

Phosphorus,  yellow 

Potassium  chlorate 

Potassium  iodide 
*Potassium  oxalate  acid 
*Potassium  permanganate 

Rennet 

Salt 

Sodium  hydroxide 
*Sodium  hyposulphite 

Sodium  nitrite 

Starch,  corn 

Sugar,  cane 

Sugar,  grape 

Sulphur,  flower 

Sulphur,  roll 

Sulphuric  acid 

Vaseline 

Zinc,  granulated  or  scrap 

Zinc,  sheet 


D.     SUMMARY  OF  COST  OF  EQUIPMENT 

1  complete  set  of  apparatus  for  demonstration.  .$16.61 

1  complete  set  for  individual  use 4.76 

1  set  of  chemicals,  not  over 12.00 

Total.  ..$33.37 


LABORATORY  MANUAL 

OF 

A  YEAR  IN  SCIENCE 

CHAPTER  I 

MATTER 

Exercise   1.    Does   Gas   Occupy  Space? 
Object:     To    determine    whether    air,    which    is    a 
gas,  occupies  space. 

Apparatus 

Glass  tumbler 

Large  glass  jar 

Wide  mouth  bottle 

Two-hole  rubber  stopper 

Thistle  tube 

Glass    tubing 

Rubber  tubing 

Clamp 

Directions:  A.  Fill 
the  glass  jar  three- 
quarters  full  of  water.  ~ 
Push  the  tumbler, 
mouth  downward,  half 
way  under  the  sur-  Fig.  i. 

15 


16 


LABORATORY  MANUAL 


face  of  the  water.    Does  the  water  rise  to  fill  the  tumbler  ? 
Does  it  rise  into  the  tumbler  at  all  ?    Now  tilt  the  tumbler 

sidewise  so  that  the  edge 
of  the  mouth  of  the  tumbler 
comes  just  above  the  sur- 
face of  the  water.  What 
happens?  Without  remov- 
ing the  tumbler,  push  it 
down  into  the  water  again. 
Does  the  water  rise  into  the 
tumbler  this  time?  In  the 
first  instance  was  the 
tumbler  empty  ?  What  did 
it  contain?  What  do  you 
conclude  concerning  this 
substance  ? 

B.  Put  the  stem  end  of 
the  thistle  tube  through 
one  of  the  holes  of  the  rub- 
ber stopper.  Into  the  other 
hole,  insert  the  piece  of 
glass  tubing.  Place  the 
stopper  in  the  mouth  of  the 
bottle  and  close  the  upper 
end  of  the  glass  tube  by 
means  of  the  rubber  tubing  and  clamp.  Now  pour  water 
into  the  bulb  of  the  thistle  tube.  Does  any  water  run 
into  the  bottle  ?  Keep  the  bulb  full  of  water.  Does  the 


Fig.   2. 


A  YEAR  IN  SCIENCE  17 

water  continue  to  run  into  the  bottle  ?    Open  the  clamp. 
What  happened?    How  do  you  account  for  the  results? 

Exercise  2.  Comparison  of  English  and  Metric 
Systems.* 

Object:  To  compare  the  English  and  metric  systems. 

Apparatus 

Compass  English  weights 

Metric  rule  Quart  measure 

English   rule  Liter  measure 

Metric  weights  Centigrade  thermometer. 

Directions:  A.  Comparison  of  the  English  and 
metric  units  of  length. 

Use  a  compass  with  sharp  steel  points,  a  metric  rule, 
and  an  English  rule.  Accurately  get  the  space  of  an 
inch  with  the  compass.  Place  the  compass  on  one  of  the 
centimeter  lines  (not  the  end  of  the  rule)  of  the  metric 
rule  and  read  as  accurately  as  you  can,  estimating  in 
tenths  of  millimeters  the  distance  of  the  inch.  Record 
in  a  tabular  form.  Now  get  the  space  of  two  inches  and 
read  the  corresponding  distance  on  the  metric  rule.  Do 
the  same  for  3,  4,  5,  6,  7,  and  8  inches.  Average  each 
reading  to  find  the  number  of  centimeters  in  an  inch. 
Get  the  general  average  of  all  your  results.  Get  the 
correct  value  from  the  instructor  or  a  physics  book. 

"A  preliminary  exercise  for  those  teachers  who  wish  to 
acquaint  the  pupils  with  the  units  of  measure  before  undertaking 
the  main  work  of  the  course. 


18  LABORATORY  MANUAL 

What  error  did  you  make?  What  is  the  reason  for 
the  error? 

B.  Measurements. 

Accurately  measure  the  length,  width,  and  thickness 
of  the  top  of  the  laboratory  table,  using  the  metric 
rule.  Calculate  the  area  of  the  top  in  square  centi- 
meters and  in  square  meters.  Also  calculate  the 
number  of  cubic  centimeters  in  the  table  top.  Change 
all  of  these  metric  readings  into  English  values.  Make 
the  same  measurements,  using  the  English  rule.  Find 
the  area  of  the  table  top  in  square  inches,  square  feet 
and  square  yards.  Compare  all  of  these  results  with 
your  calculated  results. 

C.  Examine  a  box  of  metric  weights.     Study  the 
small  or  fractional  wreights. 

What  relation  do  these  small  weights  have  to  a 
gram  weight?  Arbitrarily  select  six  different  com- 
binations of  small  and  large  weights  and  express  each 
of  these  values  in  grams.  Have  the  instructor  verify 
your  readings. 

D.  Comparison  of  the  English  and  metric  units  of 
weight. 

(a)  Weigh  a  one  pound  weight  as  accurately  as  you 
can,  using  metric  weights.     Record  your  result. 

(b)  Weigh  a  two  pound  weight  in  the  same  way. 
Find  the  average  of  both  readings.    How  many  grams 
in  a  pound? 

(c)  Weigh  an  ounce  to  find  the  number  of  grams 
to  which  it  is  equivalent.    Get  the  correct  values  from 


A  YEAR  IN  SCIENCE  19 

the  instructor.  How  much  of  an  error  did  you  make? 
How  do  you  account  for  this  error? 

E.  Comparison  of  the  English  and  metric  units  of 
volume. 

Use  a  liter  vessel,  a  quart  measure,  and  a  set  of 
metric  weights. 

(a)  Find   by    measurement,   using   water,   which   is 
larger,  a  liter  or  a  quart. 

(b)  Weigh  a  liter  of  distilled  water.     First  balance 
the  dry  liter  vessel,  then  fill  with  distilled  water  and 
weigh.     Find  the  temperature   of  the   water  with   a 
centigrade  thermometer. 

(c)  Weigh  a  quart  of  distilled  water.    Use  the  same 
method  as  you  employed  in  weighing  the  liter  of  water. 

(d)  Find  the  relation  of  a  quart  ^o-a  liter  from  your 
data  of  (c).     Ask  the  instructor  to  verify  your  results. 
How  accurate  has  your  work  been?     Does  the  tem- 
perature of  the  water  have  anything  to  do  with  its 
weight?     Can  you   think   of  reasons   for   any   errors 
that  you  may  have  made  ? 

Exercise  3.    Does  Gas  Have  Weight? 

Object:    To  determine  whether  gases  have  weight. 

Apparatus 

Balance  and  weights  Incandescent  lamp  bulb 
Hollow  brass  globe  with  (burnt  out  bulb) 

stop  cock  Bunsen  burner 

Air  pump  Blow  pipe 

Directions :  A.  On  one  pan  of  the  balance  place  the 
brass  globe.  Upon  the  other  pan  place  enough  weights 


20  LABORATORY  MANUAL 

to  balance  the  globe  evenly.     Without  disturbing  the 
weight  pan,   remove   the   globe   from  the   other  pan. 


Fig.   3. 

With  an  air  pump  exhaust  the  air  from  the  globe  and 
then  close  the  stop  cock.  Then  replace  the  globe  on 
the  pan  of  the  balance  from  which  it  was  removed. 
Do  the  two  sides  now  evenly  balance  each  other  ? 
How  do  you  account  for  this  condition?  Does  air 
then  have  weight?  Air  is  a  gas.  From  the  definition 
of  matter,  do  experiments  1  and  3  prove  that  gas  is 
matter?  Why? 

B.  The  bulb  of  an  incandescent  lamp  is  empty  save 
for  the  filament  and  a  very  slight  trace  of  gas  which 
was  not  exhausted.  Weigh  the  bulb  carefully  and 
accurately  With  the  aid  of  the  blow-pipe  direct  a 


A  YEAE  IN  SCIENCE  21 

tiny  flame  point  of  the  Bunsen  flame  upon  a  small 
area  of  the  bulb  near  the  top  where  the  diameter  is 
greatest.  As  the  glass  softens,  the  pressure  of  the  air 


Fig.    4. 

outside  will  make  a  hole.     Weigh  the  bulb  after  the 
hole  has  been  made  in  the  glass. 

Observations : 

Weight  of  empty  bulb 

Weight  of  bulb  filled  with  air 

Difference  equals  weight  of  air  in  bulb 

CHAPTER  II 

CONSTITUTION  OF  MATTER 

Exercise  4.    Diffusion  of  Liquids. 
Object:     To  determine  whether  liquids  will  diffuse 
when  in  contact. 


22 


LABOEATORY  MANUAL 


Thistle  tube 
Glass  cylinder 
Metric  rule 


Apparatus 

Saturated  solution  of 

copper  sulphate 
Distilled  water 


Directions:  Fill  the  glass  cylinder  two-thirds  full 
of  distilled  water.  Into  the  cylinder  place  the  thistle 
tube  with  the  bulb  upward.  When  the  water  is  quiet, 
slowly  pour  through  the  thistle  tube  50  cubic  centi- 
meters of  copper  sulphate  solution. 
This  must  be  done  as  carefully  as 
possible  to  avoid  mixing  the  liquids. 
What  is  now  the  relative  positions 
of  the  liquids  ?  Is  there  a  sharp  line 
of  separation  between  the  liquids? 
Why  is  the  copper  sulphate  solution 
placed  on  the  bottom  of  the  glass 
cylinder?  Measure  accurately  with 
a  metric  rule  the  height  of  the 
copper  sulphate  solution.  Record 
observations  and  allow  the  experi- 
ment to  remain  undisturbed  until 
the  next  recitation  period.  Then 
repeat  the  observations  made  above. 
5.  What  changes?  In  conclusion,  what 

have  you  learned  from  this  experiment? 

Exercise  5.  Diffusion  of  Liquids  through  a  Mem- 
brane. 

Object :  Will  liquids  diffuse  if  separated  by  an 
animal  membrane? 


A  YEAR  IN  SCIENCE 


23 


Apparatus 


Animal  membrane 

Thistle  tube 

Water 

Molasses 

Twine 

Glass  jar 

Ring  stand  and  clamp 

Rubber  tubing 


Clamp 
Card  board 

Egg 

Glass  tubing 
Sealing  wax 
Hydrochloric  acid 
Glass  tumbler 
Bunsen  burner 


Directions:  A.  Over  the  stem  end  of  the  thistle 
tube  fit  a  small  piece  of  rubber  tubing.  Close  this 
tightly  with  a  clamp.  Fill  the  bulb  of  the  tube  with 
dilute  molasses.  Over  the 
end  of  the  bulb  securely  tie 
an  animal  membrane,  being- 
careful  to  exclude  all  air 
bubbles.  From  the  ring- 
stand  suspend  the  tube  with 
the  bulb  in  a  jar  of  Avater. 
Mark  the  level  of  the 
molasses  in  the  tube.  Note 
the  color  of  the  water  in  the 
jar.  At  the  end  of  one  hour 
repeat  the  same  observations. 
Observe  again  at  the  end  of 
twenty-four  hours,. 


Fig.   6. 

What  changes  have  taken  place! 
Has-any  molasses  passed  into  the  water?  How  do  you 
know  ?  Has  any  water  passed  into  the  molasses  ?  In 
which  direction  has  diffusion  taken  place  more  rapidly  ? 
How  do  you  know? 

B.     In  the  cardboard  cut  a  hole  large  enough  so  that 


24 


LABOEATOEY  MANUAL 


the  large  end  of  the  egg  will  extend  about  %  of  an 
inch  below  the  cardboard.  On  the  small  end  of  the  egg 
break  away  the  shell  to  form  an  opening  large  enough 
to  insert  the  glass  tube,  which 
should  be  about  6  inches  long. 
Carefully  seal  the  tube  in  the  egg 
with  the  end  projecting  about  half 
an  inch  below  the  shell.  Fill  the 
tumbler  with  hydrochloric  acid. 
Place  the  cardboard  and  the  egg- 
over  it  with  the  large  end  of  the 
egg  projecting  into  the  acid.  The 
acid  gradually  dis- 
solves the  shell,  ex- 
posing the  thin  mem- 
brane underneath  it. 
When  the  shell  has 
been  removed  from 
the  end  of  the  egg, 
empty  the  acid  and 
fill  the  beaker  with 
water.  Rinse  the 
acid  off  the  egg  and 
replace  the  card- 
board and  egg  over  the  tumbler.  The  water  in  the 
tumbler  and  the  contents  of  the  egg  are  now  separated 
by  the  egg  membrane.  Allow  the  experiment  to  stand 
for  24  hours.  What  change  do  you  note  in  the  tube? 
How  do  you  account  for  this  change? 


Fig.   7. 


A  YEAR  IN  SCIENCE 


25 


Gas  generator 
Lime  water 


Exercise  6.    Diffusion  of  Gases. 

Object:    Will  gases  diffuse  when  in  contact? 

Apparatus 

Wide  mouth  bottles 
Glass  covers 

Directions:  From  a  gas  generator  fill  a  bottle  with 
carbon  dioxide.*  Carbon  dioxide  is  heavier  than  air 
and  so  displaces  the  air  which  was  in  the  bottle.  Pour 
lime  water  into  the  bottle.  By  shak- 
ing the  bottle  thoroughly,  mix  the 
lime  water  with  the  carbon  dioxide. 
What  change  do  you  note  in  the  lime 
water  ?  Such  a  change  in  lime  water 
indicates  the  presence  of  carbon 
dioxide.  From  the  generator  fill 
another  bottle  with  carbon  dioxide. 
Cover  the  bottle  with  a  glass  plate 
and  remove  it  to  your  desk.  Over 
the  mouth  of  this  bottle  invert  a 
bottle  of  air  and  then  remove  the 
glass  plate.  Allow  the  bottles  to 
stand  in  this  relation  five  minutes. 
Remove  the  upper  bottle  and  cover 
it  immediately  with  the  glass  plate, 
carbon  dioxide  in  the  upper  bottle? 
determine  this  ?  What  does  this  show  ? 


Is   there   any 
How   do   you 


*To  generate  carbon  dioxide,  place  a  few  small  pieces  of  marble 
in  a  flask  and  cover  with  dilute  hydrochloric  acid.  The  flask 
should  be  fitted  with  a  delivery  tube  through  which  the  gas  can 
pass  into  the  wide  mouth  bottle. 


26 


LABORATORY  MANUAL 


Exercise  7.     Diffusion  of  Gases.     { Demonstration.) 
Object:    Will  gases  diffuse  through  a  porous  wall? 

Apparatus 

Porous  cup  with  glass  tube  Cup  of  colored  liquid 

inserted  Belljar 

Ring  stand  Air  pump 

Directions :    From  the  ring  stand  suspend  the  porous 
cup   apparatus   with  the  free   end  of  the   glass   tube 

projecting  into  the  cup  of 
colored  liquid.  Place  the 
belljar  over  the  porous 
cup.  Is  there  any  change 
at  the  end  of  the  glass  tube 
in  the  colored  liquid  ?  With 
an  air  pump  force  air  into 
the  belljar  over  the  porous 
cup.  Is  there  any  change 
now  at  the  end  of  the  glass 
tube  in  the  colored  liquid? 
Thus  the  air  currents  have 
no  effect.  Fill  the  belljar 
with  illuminating  gas,  then 
quickly  lower  it  over  the 
porous  cup.  What  change 
of  the  glass  tube  in  the 
What  change 


Fig. 

takes    place    at 
colored  liquid? 


the    end 
Remove  the  belljar. 


do  you  now  observe?  In  the  first  instance  what  were 
the  bubbles  escaping  ?  Where  did  they  come  from  ? 
What  must  have  been  the  condition  in  the  porous  cup 


A  YEAR  IN  SCIENCE  27 

to  produce  such  a  result?  How  do  you  account  for 
it?  What  must  have  been  the  condition  to  cause  the 
liquid  to  rise  in  the  tube  when  the  belljar  was 
removed?  What  does  this  exercise  teach?  Compare 
the  rate  of  diffusion  of  gases  with  that  of  liquids;  of 
solids.  Compare  the  rate  of  diffusion  of  liquids  with 
that  of  solids. 

Exercise  8.      Mixing  of  Alcohol  and  Water. 
Object:     To  determine  the  result  of  mixing  equal 
volumes  of  alcohol  and  water. 

Apparatus 

Alcohol  96%  Burette,  100  c.c. 

Distilled  water  Clamp 

Directions :  Over  the  small  end  of  the  burette  place 
a  small  rubber  tube.  Close  the  tube  tightly  with  the 
clamp.  Into  the  open  end  of  the  burette  pour  distilled 
water  to  the  height  of  the  50  c.c.  mark.  Then  carefully 
and  slowly  pour  into  the  tube  50  c.c.  of  alcohol.  Note 
carefully  the  height  of  the  two  liquids.  By  means  of 
the  thumb  close  the  burette  and  mix  the  liquids  thor- 
oughly by  repeatedly  inverting  the  tube.  Observe 
again  the  height  to  which  the  liquids  rise.  What  does 
this  condition  show?  How  do  you  account  for  it? 


28  LABORATOEY  MANUAL 

CHAPTER  III 
EFFECT  OF  HEAT  ON  MATTER 

Exercise  9.    Effect  of  Heat  on  Solids. 
Object:     To  determine  the  effect  of  the  change  of 
temperature  on  the  volume  of  a  solid. 


Brass  ball 
Brass  ring 
Bunsen  burner 


Apparatus 

Compound  bar 
Nail  punch 
Screw  nut 


Directions :    A.    Try  the  fit  of  the  ring  over  the  ball. 
Heat  the  ball.     Will  the  ball  now  pass  through  the 

ring?  Heat  the  ring.  Will 
the  ball  now  pass  through 
the  ring?  Cool  the  ring 
by  running  tap  water  over 
it.  Will  the  ball  pass 
through  the  ring  now  ?  In 
the  same  manner  cool  the 
ball  and  try  the  fit  again. 
From  these  observations 
what  is  the  effect  of  an 
increase  of  temperature 
upon  the  volume  of  a 
solid?  What  is  the  effect 
of  a  decrease  of  tempera- 
ture? 

B.     Adjust  the  nut  on 
Fig.  10.  the  punch.  Mark  the  point 


A  YEAE  IN  SCIENCE  29 

on  the  punch  to  which  the  nut  fits.  Then  heat  the  nut 
and  adjust  it  on  the  punch  once  more.  Does  it  pass 
as  far  or  farther  on  the  punch  than  it  did  when  cold? 
Heat  the  punch  and  repeat  the  adjustment.  What  do 
you  find?  What  does  this  show?  Have  you  ever  seen 
a  blacksmith  fit  a  tire  to  a  wagon  wheel?  What  is 
the  principle  involved? 

C.  Do  all  solids  expand  and  contract  at  the  same 
rate?  To  determine  this,  use  a  compound  bar.  A 
compound  bar  consists  of  two  metals  tightly  welded  or 
riveted  together  lengthwise.  Heat  the  bar  equally  on 
both  sides  by  playing  the  flame  of  a  Bunsen  burner 
along  its  edge.  Do  you  observe  any  change  in  the 
direction  of  the  bar?  What  does  this  indicate?  Cool 
the  bar  by  running  tap  wrater  over  its  edge.  Does  the 
direction  of  the  bar  now  change  ?  How  do  you  explain 
these  results? 

Exercise  10.    Effect  of  Heat  on  Liquids. 
Object:     Does  the  volume  of  liquids  change  with 
a  change  in  temperature  ? 

Apparatus 

Test  tube  Bunsen  burner 

One-hole  rubber  stopper  Test  tube  clamp 

Glass  tube 

Directions :  A.  Fill  the  test  tube  with  cold  water. 
Into  the  mouth  of  the  tube  insert  the  rubber  stopper 
fitted  with  a  glass  tube.  Press  on  the  stopper  until  the 
water  rises  about  an  inch  in  the  glass  tube.  Marli 
carefully  the  level  of  the  water. 


30 


LABOBATOEY  MANUAL 


Heat  the  water  gently  by  playing  the  flame  of  the 
Bunsen  burner  along  the  side  of  the  test  tube.  What 
change  do  you  observe  in  the  water  level? 


Fig,   11. 

Again  mark  the  level  of  the  water.  Cool  the  water 
in  the  test  tube  by  running  tap  water  over  it,  or  by 
surrounding  the  test  tube  with  ice.  After  a  few 
minutes  note  the  level  of  the  water. 

B.  Fill  the  test  tube  with  water.  Tightly  cork  the 
filled  tube  and  after  thoroughly  drying  the  exterior  of 
the  tube,  gently  heat  it  over  the  Bunsen  flame.  Explain 


A  YEAE  IN  SCIENCE 


31 


the  result.  Did  the  amount  of  water  increase  with  the 
increase  of  temperature  ?  Did  it  decrease  with  a  lower 
temperature?  Then  how  do  you  explain  the  increase 
and  decrease  in  volume  noted  upon  heating  and  cooling 
respectively  ? 

Exercise  11.    Effect  of  Heat  on  Gases. 
Object:      To   determine   the   effect   of  a   change   of 
temperature  upon  the  volume  of  gases. 


Tost   tube 

( )ne-liole  rubber  stopper 

Bunsen  burner 


Apparatus 

Beaker  of  colored  liquid 
Test  tube  clamp 


Directions:  A.  Fit  the  stopper  with  the  glass  tube 
into  the  test  tube  as  in  the  preceding  exercise.  With 
wliat  is  the  test  tube  filled?  Is  this  a  gas?  See  Exercise 


32  LABORATORY  MANUAL 

1.  Place  the  projecting  end  of  the  glass  tube  into  the 
beaker  of  colored  liquid.  Heat  the  tube  gently  with  a 
Bunsen  flame.  Observe  carefully  all  changes.  Without 
changing  the  apparatus  allow  the  gas  in  the  test  tube 
to  cool.  What  change  do  you  now  observe?  How  do 
you  account  for  the  change  ? 

B.  Tightly  cork  a  test  tube  filled  with  air.  Gently 
heat  the  tube  over  the  Bunsen  flame.  Explain  the 
result.  Does  this  change  indicate  an  increase  in  the 
amount  of  gas  in  the  test  tube  or  in  its  volume  ?  From 
the  last  three  exercises  what  is  the  effect  of  the  increase 
of  temperature  upon  the  intermolecular  spaces  ?  Upon 
the  molecules?  The  effect  of  the  decrease  of  tempera- 
ture upon  the  intermolecular  spaces?  Upon  the  mole- 
cules ? 

Exercise  12.    Cohesion,  Adhesion,  and  Gravity. 
Object:    A  study  of  forces  acting  between  molecules 
and  between  masses. 

Apparatus 

Spring  balance  Battery  jar 

Circular  glass  plate  Sealing  wax 

Directions:  By  means  of  sealing  wax,  attach  three 
strings  at  equidistant  points  near  the  margin  of  the 
glass  plate.  Tie  the  ends  of  the  strings  together  and 
suspend  the  plate  from  the  hook  of  the  spring  balance. 
(The  glass  plate  must  hang  horizontally.)  Record  the 
weight  of  the  glass  plate.  Then  lower  the  apparatus 
over  the  battery  jar  filled  with  water,  until  the  plate 
touches  the  water.  Slowly  lift  the  balance,  at  the 


A  YEAR  IN  SCIENCE 


33 


same  time  noting  any  changes  in  the  reading  on  the 
index  of  the  balance.  Continue  to  lift  the  balance. 
What  happens?  Examine  the  under  surface  of  the 
plate.  What  do  you  find  there? 
Does  this  indicate  that  the  plate 
was  separated  from  the  water  or 
that  the  water  particles  were 
pulled  apart? 

Thus  it  will  be  seen  that  two 
forces  were  acting,  the  one  holding 
the  molecules  of  water  together, 
called  cohesion,  the  other  holding 
the  plate  to  the  water,  adhesion. 
Which    in    this    ex- 
periment    was     the 
greater?      With    the 
water  still  adhering, 
hold     the     plate     in 
a    vertical    position. 
What  happens  to  the 
water?      This    third 
force      causing      the 
water     to     drop     is"" 
called  gravity. 

Which     of     these 
forces    acts    between  Fi§r-  13- 

molecules  of  the  same  kind?     Between  molecules  of 
different  kinds?    Between  masses? 


34  LABORATORY  MANUAL 

CHAPTER  IV 
MEASUREMENT  OF  TEMPERATURE 

Exercise  13.    Thermometers. 

Object:     A  comparative  study  of  thermometers. 

Apparatus 

Fahrenheit   thermometer  Metric   rule 

Centigrade   thermometer 

Directions:  Examine  a  thermometer  carefully. 
How  is  it  made?  Note  the  markings  on  the  scale. 
What  do  they  indicate?  What  two  points  on  the 
thermometer  seem  of  special  importance?  On  this, 
the  centigrade  thermometer,  zero  degree  is  the  freezing 
point  of  water  and  100  degrees  the  boiling  point.  Can 
you  suggest  a  way  of  determining  these  points  ?  After 
they  are  located  how  would  you  find  the  length  on 
the  scale  of  one  degree? 

On  your  note  paper  make  a  drawing  of  a  thermom- 
eter. On  the  right  side  of  the  line  place  two  points, 
one  for  the  boiling  point,  the  other  for  the  freezing 
point.  Between  these  points  mark  the  10,  20,  30,  etc., 
to  100  degrees.  Continue  the  line  representing  the 
thermometer  tube  below  0  degrees  far  enough  to  admit 
negative  40  degrees.  On  the  left  side  mark  212  degrees 
opposite  boiling  and  32  degrees  opposite  freezing. 
How  many  degrees  on  this,  the  Fahrenheit  ther- 
mometer, are  there  between  freezing  and  boiling?  On 


A  YEAB  IN  SCIENCE  35 

the  side  opposite  the  10,  20,  30  (degrees),  etc.,  markings 
of  the  centigrade  thermometer,  fill  in  the  corresponding 
numbers  of  the  Fahrenheit  thermometer.  Find  the 
value  of  one  degree  centigrade  in  terms  of  Fahrenheit 
degrees.  Find  the  value  of  one  degree  Fahrenheit  in 
terms  of  the  centigrade  degree. 

Problems:  1.  Fifteen  degrees  C.  are  equal  to  how 
many  degrees  F.  ? 

2.  Forty-five   degrees   F.   are   equal  to   how   many 
decrees  C.  ? 

3.  The  centigrade  thermometer  registers  21  degrees. 
What   does   the   Fahrenheit   thermometer   register   at 
the  same  time? 

4.  The    Fahrenheit   thermometer   registers    14   de- 
grees.      What     does     the     centigrade     thermometer 
register  at  the  same  time? 

5.  What  is  the  principle  upon  •  which  the  construc- 
tion of  the  thermometer  is  based? 

Exercise  14.    Measurement  of  the  Heat  of  a  Flame. 

It  is  a  well-known  fact  that  if  any  substance  is  held 
in  a  flame,  its  temperature  is  increased.  The  cause  of 
this  increase  is  called  heat.  To  measure  this  increase 
sonic  unit  of  measure  is  necessary.  To  this  unit  the 
name  gram-calorie  has  been  given.  A  gram-calorie  is 
lh<  (unounf  of  heal,  necessary  to  raise  one  gram  of  water 
<»><  degree  ccnliyrade-. 

Object:  To  determine  the  amount  of  heat  given  off 
by  a  given  flame  in  one  minute. 


36 


LABORATORY  MANUAL 

Apparatus 


Flask 
Thermometer 

Asbestos  cover  for  liask 
Flame  protector 


Wire  gauze 
Bunsen  burner 
Ring  stand 
Graduate,  100  c.c. 


Directions:  A.  Place  100  c.c.  of  water  in  the  flask 
and  set  it  aside.  From  the  ring  stand  suspend  the  flame 
protector.  Adjust  it  in  such  a  manner  that  the  lower 

part  of  the  protector  fits 
over  the  upper  part  of  the 
Bunsen  burner.  Then 
place  the  wire  gauze  upon 
the  ring.  Light  the  Bun- 
sen  burner  and  regulate 
the  gas  and  air  for  a  blue 
flame  of  moderate  size. 
Place  the  burner  under 
the  protector.  Do  not 
change  these  adjustments 
until  the  experiment  is 
3  completed. 

Take  the  temperature  of 

the  water  in  the  flask.  Cover  the  flask  with  an  asbestos 
cover,  and  place  it  on  the  wire  gauze,  noting  the  exact 
time  this  is  done.  Note  and  record  the  rise  in  tempera- 
ture of  the  water  each  minute  for  ten  minutes.  Then 
turn  off  the  gas. 

What  is  the  average  number  of  degrees  of  rise  of 
temperature  per  minute  ?  How  many  c.c.  of  water  were 


A  YEAR  IN  SCIENCE 


37 


increased  this  number  of  degrees  per  minute?  Then 
how  many  calories  of  heat  was  your  flame  giving  off 
per  minute? 

Tabulate  results  as  follows : 


Am  't  of  Water 

Temp. 

Time 

Inc.  per  min. 

Ave.Inc. 

Beginning 

1 

2 

3 

4 

5 

6 

7 

Q 

O 

9 

End 

10 

B.  With  the  gas  adjustment  the  same  throughout, 
prepare  flasks  as  follows : 

One  containing  100  c.c.  water. 
200  c.c.      " 
300  c.c.      " 
400  c.c.      " 
500  c.c.      " 

The  water  in  each  flask  should  be  the  same  tempera- 
ture (room  temp.)  at  the  beginning  of  the  experiment. 
With  the  bulb  of  the  thermometer  in  the  water  in  the 
flask,  heat  each  until  the  water  begins  to  boil.  Note 
carefully  in  each  instance  the  length  of  time  necessary 


38  LABOEATOEY  MANUAL 

to  bring  each  separate  quantity  to  the  boiling  point. 
The  product  of  the  quantity  of  water  multiplied  by  the 
number  of  degrees  its  temperature  was  raised,  divided 
by  the  number  of  minutes  required  for  bringing  the 
water  to  the  boiling  point,  will  give  you  the  approxi- 
mate amount  of  heat  given  off  by  the  name  per  minute. 
If  you  make  a  number  of  tests  as  indicated  above,  the 
average  of  the  results  will  give  you  a  more  accurate 
idea  of  the  available  heat  given  off  by  your  flame  per 
minute. 

CHAPTER  V 

CHANGES  IN  THE  STATE  OF  MATTER 

Exercise  15.    Change  from  a  Solid  to  a  Liquid. 
Object :     To  determine  the  heat  necessary  to  convert 
one  gram  of  ice  to  water. 

Apparatus 

Cracked  ice  Chemical  thermometer 

Balance  and  weights  Bunsen  burner 

Hot  water  Tin  beaker 

Ring  stand  Asbestos  cover 

Directions:  Surround  the  tin  beaker  with  the 
asbestos  cover  and  ascertain  the  weight  of  both.  Into 
the  beaker  pour  200  c.c.  of  Avater  at  60  degrees  C.  Now 
obtain  the  weight  of  the  beaker  and  water.  Break  75 
grams  of  ice  into  small  pieces.  After  noting  the  exact 
temperature  of  the  water  in  the  beaker,  wipe  dry  the 
pieces  of  ice  and  drop  them  into  the  water  piece  by 


A  YEAR  IN  SCIENCE  39 

piece.  When  the  ice  is  almost  melted,  note  again  the 
exact  temperature  of  the  water.  Weigh  again  the 
beaker  and  its  contents.  Tabulate  the  data  as  follows : 

1.  Weight  of  beaker  and  cover. 

2.  Weight  of  hot  water  and  beaker. 

3.  Weight  of  hot  water  (calculated). 

4.  Weight  of  beaker  and  water  at  end  of  experi- 
ment . 

5.  Weight  of  ice   (calculated). 

6.  Temperature  of  water  before  ice  was  added. 

7.  Temperature  of  water  after  ice  was  melted. 

8.  Loss  in  temperature  of  water  (calculated). 

9.  Increase  in  temperature  of  ice  (calculated). 

Multiply  the  weight  of  the  hot  water  by  its  loss  in 
temperature  to  obtain  the  number  of  calories  required 
to  melt  the  ice  and  raise  it  to  the  final  temperature. 
Multiply  the  weight  of  the  ice  by  its  increase  in  tem- 
perature to  obtain  the  number  of  calories  used  in 
raising  its  temperature.  The  difference  between  these 
results  will  give  the  number  of  calories  used  in  melting 
the  given  amount  of  ice.  How  many  calories  are 
required  to  melt  one  gram  of  ice? 

Why  is  the  temperature  of  the  atmosphere  near  a 

:dy  of  freezing  water  higher  than  the  temperature 
the  atmosphere  a  little  distance  away? 
Exercise  16.    Solution. 

Object:  To  show  the  effect  of  dissolving  salt  upon 
the  temperature  of  Avater. 


40  LABOEATOEY  MANUAL 

Apparatus 

Beaker  Thermometer 

Salt 

Directions :  Half  fill  a  beaker  with  water.  Carefully 
observe  and  record  its  temperature.  Into  the  water 
put  several  teaspoonfuls  of  salt.  Quickly  insert  the 
thermometer  into  the  beaker.  Do  you  note  any 
changes  in  the  temperature?  What  change  is  taking 
place  in  the  salt?  What  is  necessary  to  produce  this 
change  ?  For  your  answer  refer  to  Exercise  15.  Then 
how  do  you  explain  the  change  in  temperature  which 
occurs  ?  Why  is  salt  mixed  with  the  ice  in  an  ice  cream 
freezer?  When  snow  melts,  what  effect  does  this  have 
on  the  surrounding  temperature?  Does  this  tend  to 
increase  or  decrease  the  rate  of  melting?  Of  what 
advantage  is  this? 

Exercise  17.    Change  from  Liquid  to  Solid. 
Object:    To  determine  the  effect  on  the  temperature 
of  a  substance  when  it  changes  from  a  liquid  to  a  solid. 

Apparatus 

Hypo  Graduate 

Flask  Bunsen  burner 

Thermometer  Wire  gauze 

Cotton  Ring  stand 

Directions:  Into  the  flask  place  10  c.c.  of  water. 
To  this  add  50  g.  of  hypo.  Slowly  heat  the  flask 
until  all  of  the  hypo  is  dissolved.  Close  the  mouth 
of  the  flask  with  some  cotton  and  very  carefully  set 
it  aside  to  cool.  Take  every  precaution  not  to  disturb 


A  YEAE  IN  SCIENCE  41 

the  flask  while  it  is  cooling.  When  it  feels  cool,  re- 
move the  cotton,  insert  the  thermometer  into  the  liquid, 
and  note  the  temperature.  Shake  the  liquid  until  it 
begins  to  crystallize.  As  it  does  so,  carefully  observe 
the  changes  in  temperature.  Explain  these  results. 
What  effect  does  a  body  of  water  which  is  freezing 
have  upon  the  temperature  of  the  surrounding 
atmosphere  ?  Why  ? 

Exercise  18.    Change  from  a  Liquid  to  a  Gas. 
Object:    To  determine  the^heat  necessary  to  convert 
1  c.c.  of  water  into  steam  or  water  vapor. 

Apparatus 

Flask  Wire  gauze 

Thermometer  Bunsen  burner 

Asbestos  cover  for  flask  Ring  stand 

Flame  protector  Graduate,   100  c.c. 

Directions:  Set  up  apparatus  as  in  Exercise  14. 
Obtain  the  heat  of  the  flame  as  in  that  exercise.  Con- 
tinue to  heat  the  water,  noting  the  exact  instant  when 
it  begins  to  boil.  Allow  it  to  boil  for  ten  minutes. 
Turn  off  the  gas  and  set  the  water  aside  to  cool.  After 
cooling,  measure  the  water  remaining  in  the  flask. 

Tabulate  data  as  follows : 

1.  Amount  of  water  at  beginning. 

2.  Amount  of  water  at  end. 

3.  Loss  in  water  (calculated). 

4.  Calories  given  off  by  flame  per  minute   (calcu- 
lated). 

5.  Length  of  time  water  boiled. 


42 


LABOKATOKY  MANUAL 


6.  Number  of  calories  used  in  boiling  away  water 
(calculated). 

7.  Number  of  calories  required  to  boil  away  1  c.c. 
of  water  (calculated). 

8.  Did  the  temperature  rise  during  boiling? 

9.  What  became  of  the  heat? 

Exercise  19.    Effect  of  Pressure  on  Boiling-  Point. 
Object:    To  show  the  effect  of  lowering  the  pressure 
on  the  boiling  point  of  water. 


Apparatus 


Air  pump 
Flask 

Thermometer 
Bun  sen   burner 
Ring  stand 


Wire  gauze 
Belljar 
Vaseline 
Rubber  stopper 
Beaker 


Fig.  15. 

Directions :    A.    Half  fill  a  flask  with  Avater  and  place 
it  on  a  ring  stand  over  the  flame  of  a  Bunsen  burner. 


A  YEAE  IN  SCIENCE  43 

Heat  the  water  to  about  60° C.  Then  remove  the 
llask  and  place  it  on  the  receiver  of  the  air  pump. 
Rub  the  edge  of  the  belljar  with  vaseline  and  then 
lower  it  over  the  flask.  Exhaust  the  air-  from  under 
the  belljar.  What  happens  to  the  water?  What  is 
the  temperature  at  which  water  boils  under  ordinary 
conditions?  How  can  you  explain  the  results  of  this 
exercise? 

If  the  belljar  is  sufficiently  high,  the  thermometer 
should  be  left  in  the  flask.  Repeat  the  experiment 
several  times,  each  time  recording  the  temperature  at 
which  the  water  boils. 

B.  Again  half  fill  the  flask  with  water  and  heat  it 
until  it  boils.  After  it  has  boiled  about  two  minutes, 
insert  the  rubber  stopper.  Allow  the  flask  to  cool  a 
few  minutes  and  then  invert  it  on  the  ring  of  the  ring- 
stand.  Pour  cold  water  over  the  flask.  What  happens 
to  the  water?  Why?  Will  the  boiling  point  of  water 
be  above  or  below  100°C.  on  top  of  a  mountain?  Why? 
It  is  impossible  to  cook  potatoes  by  boiling  on  top  of  a 
very  high  mountain.  Why  ? 

Exercise  20.    How  Water  is  Distilled. 

Object:     To  determine  how  substances  dissolved  in 

water  may  be  separated  from  it. 
Apparatus 

I' lask  Bunseii    burner 

One-bole  rubber  stopper  Ring   stand 

Delivery  tube  \Yire  jjauze 

Test  tube  Salt 

Beaker 


44 


LABORATORY  MANUAL 


Directions:  Into  a  flask  put  about  200  c.c.  of  water 
and  3  or  4  teaspoonfuls  of  salt.  Stir  or  shake  the  mix- 
ture until  all  the  salt  has  dissolved.  Then  insert  the 

delivery  tube  through 
the  stopper  and  close 
the  flask.  Heat  the 
solution  to  boiling.  Put 
the  free  end  of  the  tube 
into  a  test  tube  which 
is  surrounded  by  cold 
water.  Keep  the  water 
cold  by  adding  ice  or 
snoAv.  Boil  the  water 
in  the  flask  for  about 
5  minutes.  Taste  the 

^S^--C  -^2*^ 

F[S-  16-  liquid  that  has  distilled 

over  into  the  test  tube.    Is  there  any  salt  present  ?    Of 
what  commercial  value  is  distillation? 

Exercise  21.    Evaporation. 

Object:     To  show  a  result  of  evaporation. 


Thermometer 
Chloroform 


Apparatus 

Absorbent  cotton 


Directions:  Wrap  a  small  bit  of  cotton  tightly 
about  the  bulb  of  a  thermometer.  Record  the  reading 
of  the  thermometer.  Saturate  the  cotton  with  chloro- 
form and  wave  the  thermometer  in  the  air  to  evap- 
orate the  chloroform.  -As  it  evaporates  what  change 


A  YEAK  IN  SCIENCE 


45 


in  temperature  do  you  note?    How  do  you  account  for 
this  change?    See  Exercise  18. 

Water,  ether,  or  alcohol  may  be  used  in  place  of  the 
chloroform.  Place  a  drop  of  chloroform  on  the  back 
of  the  hand.  What  is  the  sensation  produced  as  the 
chloroform  evaporates?  What  is  the  principle  used 
in  the  manufacture  of  ice  by  the  use  of  ammonia? 


CHAPTER  VI 

PHYSICAL  AND  CHEMICAL  CHANGES 

Exercise  22.     Physical  Change. 
Object:     To    determine    the    nature    of    a    physical 
change. 

Apparatus 

Salt 

Distilled  water 
Evaporating  dish 
Wire  gauze 
Bunsen  burner 
Glass  stirring  rod 
Ring  stand 

Directions:  Place  some 
salt  in  an  evaporating 
dish.  Cover  it  with  dis- 
tilled water.  Stir  it  with, 
the  glass  rod.  What 
happens  to  the  salt  ?  Place  Fis.  n. 

the   evaporating  dish   with  the   solution   on  the   wire 
gauze  over  the  flame.     Heat  the  solution  slowly  until 


46  LABORATORY  MANUAL 

all  the  liquid  has  evaporated,  being  careful  not  to 
burn  the  substance  left  in  the  dish.  Taste  the  residue. 
What  is  it?  Has  its  form  changed?  Its  nature? 
Changes  which  do  not  involve  a  change  in  the  composi- 
tion of  substances  are  called  physical  changes. 

Exercise  23.     Chemical  Change. 
Object:      To    determine    the    nature    of    a    chemical 
change. 

Apparatus 

Sugar  Wire  gauxe 

Sulphuric  acid  Test  tube 

Evaporating  dish  Potassium   iodide    crystals 

Bunsen  burner  Mercuric    chloride    crystals 

Glass  stirring  rod  (poison) 

Ring  stand  Mortar  and  pestle 

Directions :  A.  Cover  some  sugar  in  the  evaporating 
dish  with  sulphuric  acid.  Stir  the  substance  with  the 
glass  rod.  What  happens?  Place  the  solution  on  the 
wire  gauze  and  slowly  heat  it.  What  happens?  Does 
the  resulting  substance  resemble  either  the  acid  or  the 
sugar  with  which  you  started? 

Changes  which  involve  a  change  in  the  composition 
of  substances  and  result  in'  the  formation  of  new  sub- 
stances are  called  chemical  changes. 

Classify  the  following  under  the  head  of  chemical 
or  physical  change  respectively :  A  change  from  ice  to 
water;  water  to  ice;  water  to  gas;  gas  to  water;  action 
of  hydrochloric  acid  on  marble  as  used  in  Exercise  6; 
burning  of  wood;  cider  to  vinegar. 

B.     The  following  experiments  are  to  be  performed 


A  YEAR  IN  SCIENCE  47 

by  instructor  only :  Rub  together  in  the  mortar  a  few 
crystals  of  potassium  iodide  with  a  few  of  mercuric 
chloride.  What  evidence  appears  that  a  new  substance 
is  formed  ? 

Dissolve  a  few  crystals  of  potassium  iodide  in  water 
in  a  test  tube.  In  another  dissolve  about  an  equal 
quantity  of  mercuric  chloride.  Warm  water  will  hasten 
solution.  Pour  a  little  of  the  potassium  iodide  solu- 
tion into  a  third  test  tube,  and  gradually  add  mercuric 
chloride  solution  to  it.  The  red  precipitate  is  the 
same  substance  as  was  formed  when  the  different  kinds 
of  crystals  were  rubbed  together. 

CHAPTER  VII 

CHEMICAL  PHENOMENA 

Exercise  24.    Mechanical  Mixture. 

Object:     To  demonstrate  a  mechanical  mixture. 

Iron  filings  Wire  gauze 

Salt  Ring  stand 

Magnet  Glass  stirring  rod 

Beaker  Mortar  and  pestle 

Evaporating  dish  Funnel 

Bunsen  burner  Filter   paper 

Directions:  Mix  together  in  a  mortar  2  grams  of 
salt  and  2  grams  of  iron  filings.  By  means  of  a  magnet, 
try  to  separate  the  iron  from  the  salt.  What  is  the 
result?  Now  pour  the  contents  of  the  mortar  into  a 
beaker.  Add  20  c.c.  of  water  to  the  mixture,  and  with 


48 


LABOEATOEY  MANUAL 


a  glass  stirring  rod,  stir  until  the  salt  is  all  dissolved. 

Filter   and   evaporate   the   filtrate    (the   liquid   which 

passed  through  the  filter)  to  dryness,  using  the  evapo- 
rating dish.  What  is  the 
substance  left  in  the 
evaporating  dish?  To  de- 
termine this,  taste  it. 
With  the  magnet,  test  the 
substance  left  on  the  filter 
paper.  What  is  it  ?  In  mix- 
ing together  iron  filings 
and  salt  were  the  prop- 
erties of  either  changed? 
If  two  or  more  sub- 

stances     are     placed     to- 

Fig-  18-  gether,    and    each   retains 

its  original  properties,  the  resulting  substance  is  called 

a  mechanical  mixture. 

Exercise  25.    Chemical  Synthesis. 

Object:     To  determine  the  formation  of  compounds. 


Apparatus 

Test  tube  holder 
Bunsen  burner 
Mortar  and  pestle 


Iron  filings 
Flowers  of  sulphur 
Test  tube 
Magnet 

Directions:  Note  carefully  the  nature  of  the  ele- 
ments, iron  filings  and  sulphur.  Grind  together  in  a 
mortar  2  grams  of  sulphur  and  2  grams  of  iron  filings. 
The  grinding  is  to  be  done  very  thoroughly.  With  a 


A  YEAR  IN  SCIENCE  49 

magnet  try  to  separate  the  iron  from  the  sulphur. 
What  is  the  result?  Place  the  mixture  in  a  clean, 
dry  test  tube.  With  the  test  tube  holder,  hold  the  tube 
over  the  Bunsen  flame  until  the  contents  begin  to  glow. 
Remove  it  from  the  flame  until  the  glow  ceases,  then 
heat  the  tube  again  very  strongly  for  a  few  minutes. 
Remove  the  tube  from  the  flame.  When  cool,  break 
the  tube.  Examine  the  contents.  Test  them  with  the 
magnet.  What  changes  have  the  substances  under- 
gone? The  new  substance  is  a  chemical  compound 
called  iron  sulphide,  resulting  from  the  chemical  union 
of  the  elements,  iron  and  sulphur. 

Another  experiment  to  show  chemical  synthesis  is 
to  grind  together  in  a  mortar,  mercury  and  iodine 
crystals. 

Exercise  26.    Chemical  Analysis. 

Object:    The  decomposition  of  compounds. 

Apparatus 

Mercuric  oxide  Pine  splinter 

Hard  glass  test  tube  Bunsen  burner 

Test  tube  holder 

Directions:  Such  characteristics  as  hardness,  color, 
form,  etc.,  are  known  as  the  physical  properties  of  a 
substance. 

Note  carefully  the  physical  properties  of  mercuric 
oxide.  Place  a  very  small  amount  of  it  in  a  test  tube 
and  heat  it  very  thoroughly.  With  the  test  tube  in 
the  flame,  insert  a  glowing  pine  splinter  into  the  tube. 
Continue  heating  the  mercuric  oxide.  What  change 


50  LABORATORY  MANUAL 

do  you  note  in  the  ember?  Where  does  the  substance 
come  from  that  causes  this  change?  This  same  sub- 
stance is  found  in  the  air  and  is  called  oxygen. 

Examine  the  sides  of  the  tube  a  little  above  the  mer- 
curic oxide.  What  do  you  find  there?  From  what 
substance  did  it  come?  Scrape  it  from  the  sides  of 
the  tube  and  shake  it  out  on  to  a  piece  of  paper.  Thus 
mercuric  oxide  has  been  separated  by  means  of  heat 
into  its  elements,  oxygen  and  mercury.  The  process 
of  separating  or  decomposing  a  compound  into  its  ele- 
ments is  known  as  chemical  analysis. 

CHAPTER  VIII 

CHEMICAL  ELEMENTS 

Exercise  27.     Carbon. 

Object:  To  determine  some  of  the  properties  of 
carbon. 

Apparatus 

Wood  charcoal  Pine  splinter 

Lime  water  Crushed  marble 

Test  tube  Dilute  hydrochloric  acid 

Beaker 

Directions :  One  of  the  forms  in  which  carbon  occurs 
is  charcoal.  Examine  a  stick  of  wood  charcoal.  What 
is  the  color?  Is  it  soluble  in  water?  Light  the  stick 
of  charcoal.  Does  it  burn  freely?  Does  it  give  off  any 
odor  in  burning?  Thrust  the  lighted  charcoal  into  the 
mouth  of  a  test  tube  containing  some  clear  lime  water. 


A  YEAE  IN  SCIENCE  51 

Allow  it  to  burn  in  the  tube  for  a  minute,  then  remove 
it  and  mix  the  lime  water  with  the  gas  in  the  tube 
by  shaking.  What  is  the  effect  of  the  gas  on  the  lime 
water?  Then  what  must  this  gas  be?  (See  Exercise  6.) 

Rinse  the  test  tube  with  water.  Again  place  some 
lime  water  in  it.  Light  the  pine  splinter  and  thrust  it 
into  the  test  tube.  Remove  the  splinter  and  shake  the 
lime  water.  What  change  do  you  note  in  the  lime 
water?  Does  wood  contain  carbon? 

Place  a  few  pieces  of  marble  in  a  clean  test  tube. 
Pour  on  it  a  little  dilute  hydrochloric  acid.  What  hap- 
pens? This  is  a  chemical  action  between  the  marble 
and  the  acid.  Over  the  mouth  of  this  test  tube  place 
the  mouth  of  another  to  collect  some  of  the  gas  given 
off.  Remove  the  second  test  tube,  pour  into  it  some 
lime  water  and  shake.  What  is  the  effect  on  the  lime 
water?  What  does  this  indicate?  Hydrochloric  acid 
contains  no  carbon.  Does  marble? 

What  are  the  properties  of  carbon  as  found  in  char- 
coal? In  what  substances  did  you  find  carbon?  What 
other  forms  of  carbon  do  you  know? 

Exercise  28.     Phosphorus.     (Demonstration.) 
Object:     To   determine  some   of  the  properties   of 
phosphorus. 

Apparatus 

Yellow  phosphorus  Forceps 

Ivcd  phosphorus  Knife 

Evaporating  dish  Filter  paper 

Directions:     (('ATTION — Yellow  phosphorus  must  be 


52  LABOEATOEY  MANUAL 

kept  under  water  and  cut  under  water.  It  must  not 
be  allowed  to  come  in  contact  with  the  bare  skin.) 

With  the  forceps  place  a  small  piece  of  yellow  phos- 
phorus in  the  .evaporating  dish,  which  has  been  filled 
with  water.  Cut  off  a  piece  with  the  knife.  Does  it  cut 
easily?  What  is  the  appearance  of  the  new  cut  sur- 
face ?  What  is  the  consistency  of  phosphorus  ?  Pick  up 
a  small  piece  with  the  forceps  and  hold  it  in  the  air  a 
moment.  What  takes  place?  Does  phosphorus  give 
off  an  odor  in  burning?  Why  is  it  kept  under  water? 
Rub  phosphorus  on  a  piece  of  filter  paper  and  examine 
the  paper  in  the  dark  room.  What  do  you  see?  Will 
phosphorus  burn  at  a  low  temperature? 

Place  a  small  piece  of  freshly  cut  phosphorus  in  a 
dish  of  water  exposed  to  the  light.  Cover  with  a  bell 
jar  and  leave  for  at  least  48  hours.  Does  any  change 
in  color  occur  ?  Examine  a  small  quantity  of  red  phos- 
phorus. Compare  in  all  details  its  properties  with 
those  of  yellow  phosphorus.  What  is  the  difference 
between  an  ordinary  and  a  safety  match? 

Exercise  29.    Sulphur. 

Object:  To  determine  some  of  the  properties  of 
sulphur. 

Apparatus 

Flowers  of  sulphur  Beaker 

Deflagrating  spoons  Silver  spoon 

Eoll  sulphur  Bunsen  burner 

Test  tube  Test  tube  holder 

Directions :     Examine  a  little  of  the  flowers  of  sul- 


A  YEAR  IN  SCIENCE  53 

phur.  What  is  its  nature?  Color?  Has  it  any  odor? 
Taste?  Place  some  of  it  in  a  small  beaker  and  cover 
with  water.  Does  it  dissolve? 

With  a  very  low  flame  slowly  heat  a  little  sulphur 
in  a  test  tube.  What  change  takes  place  ?  What  is  its 
color?  Continue  to  heat  slowly  and  watch  very  care- 
fully the  change  in  consistency  and  color.  When  the 
substance  thickens  and  turns  a  darker  color,  continue 
to  heat  it  until  it  becomes  a  thin  liquid  and  then  pour 
part  of  it  into  a  beaker  of  cold  water.  Immediately 
work  the  substance  in  the  water  with  the  fingers. 
What  is  its  nature?  Is  it  elastic? 

Continue  to  heat  the  sulphur  in  the  test  tube.  What 
collects  on  the  sides  of  the  tube?  What  is  it?  Place 
a  little  sulphur  in  the  deflagrating  spoon  and  ignite  it. 
Does  it  burn  easily?  What  is  the  color  of  the  flame? 
Do  the  fumes  have  an  odor?  When  sulphur  burns  it 
forms  a  gas  called  oxide  of  sulphur,  or  sulphur  dioxide. 
Examine  some  roll  sulphur.  How  does  it  differ  from 
the  flowers  of  sulphur? 

Place  some  sulphur  in  the  bowl  of  a  silver  spoon  or 
on  a  silver  coin.  Heat  it  slightly.  What  is  the  effect 
of  sulphur  on  silver?  The  compound  formed  is  called 
sulphide  of  silver. 

Enumerate  the  properties  of  sulphur  you  have 
learned. 

Exercise  30.    Iron. 

Object :    To  determine  some  of  the  properties  of  iron. 


54  LABOEATOEY  MANUAL 

Apparatus 

Iron  wool  Acid   potassium   oxalate 

Iron  filings  Acetic  acid 

Magnet  Ammonium  hydroxide 

Beaker  Sulphuric  acid 
Oxalic  acid 

Directions:  A.  Place  some  of  the  iron  filings  on  a 
piece  of  paper.  Slowly  bring  the  magnet  in  contact 
with  the  filings.  Raise  the  magnet.  Are  there  filings 
attached  to  it?  Are  other  things  attracted  to  it  in  the 
same  way?  To  answer  this  question  try  the  magnet 
on  a  silver  coin,  a  penny,  a  pin,  a  piece  of  gold,  etc. 

Moisten  some  iron  wool  and  set  it  aside  in  a  beaker 
for  forty-eight  hours.  What  is  the  appearance  of  the 
iron  wool  at  the  end  of  that  time? 

Do  you  know  what  this  reddish  deposit  is?  This  is 
a  compound  which  iron  forms  with  the  oxygen  of  the 
air  in  the  presence  of  moisture.  From  your  general 
observations  Avhat  other  properties  of  iron  could  you 
add  to  this  list? 

B.  Linen,  cotton,  and  other  textiles  frequently 
become  soiled  with  such  a  reddish  deposit,  and  a  "rust 
stain"  results.  Being  insoluble  in  water  and  alkalies, 
such  stains  are  not  removed  by  the  ordinary  washing 
processes.  However,  rust  or  iron  oxide  is  converted 
to  a  soluble  salt  by  the  action  of  suitable  acids. 

Stain  several  pieces  of  white  cotton  cloth  with  iron 
rust.  This  may  be  done  by  placing  moistened  iron 
filings  on  the  cloth  and  leaving  them  for  about  thirty 


A  YEAR  IN  SCIENCE  55 

minutes.      Treat    each    separately    with    one    of    the 
following : 

1.  Dilute  sulphuric  acid. 

2.  Dilute  sulphuric  acid,  then  wash  and  neutralize 
with  weak  ammonium  hydroxide. 

3.  Dilute  acetic  acid;  wash,  etc.,  as  in  2. 

4.  Oxalic  acid,  dissolved  in  hot  water;  wash,  etc. 

5.  Acid  potassium  oxalate,  dissolved  in  hot  water ; 
wash,  etc. 

Which  is  the  most  rapid  and  effective  in  action? 
Examine  specimens  number  one  and  number  two  after 
several  days  have  elapsed.  Has  the  acid  attacked  the 
cotton  as  well  as  dissolved  the  stain?  Why  should  the 
cloth  always  be  thoroughly  washed  after  treatment? 
What  is  the  added  advantage  of  using  ammonia  water  ? 

Exercise  31.    Oxygen. 

Object:  To  determine  some  of  the  properties  of 
oxygen. 

Apparatus 

Potassium   chlorate  Bunsen   burner 

Manganese  dioxide  Large  mouth  bottles 

Florence  flask  Glass  plates 

Rubber  stopper    (one-hole)  Deflagrating  spoon 

Pneumatic  trough  Charcoal 

Delivery  tube  Sulphur 

Ring  stand  Pine  splinter 

Wire  gauze  Lime  water 

Directions:  Place  in  the  flask  a  mixture  of  four 
parts  of  potassium  chlorate  and  one  part  of  manganese 
dioxide.  Insert  into  the  mouth  of  the  flask  the  rubber 


56 


LABORATORY  MANUAL 


stopper  carrying  the  delivery  tube.  Place  the  free 
end  of  the  tube  in  the  pneumatic  trough.  Place  the 
flask  on  the  wire  gauze  over  the  flame  of  a  Bunsen 


Fig.   19. 

burner  and  heat  gently.  By  heating  the  mixture  a  gas, 
called  oxygen,  is  given  off.  Allow  the  first  gas  from 
the  flask  to  escape.  Why?  Then  place  the  delivery 
tube  under  the  mouth  of  an  inverted  bottle  filled  with 
water.  When  the  bottle  is  filled  with  oxygen,  cover 
it  with  a  glass  plate  and  set  it  aside.  Fill  five  other 
bottles  with  oxygen  in  the  same  manner. 

1.  Examine  the  gas  in  one  bottle.    Has  it  any  color? 
Any  odor? 

2.  Place   a  piece   of   charcoal   in   the   deflagrating 
spoon  and  heat  it  until  it  glows.    Quickly  thrust  it  into 
a  bottle  of  oxygen.     Note  the  result.     What  property 
does   this   show   oxygen   to   possess?     What   are   the 


A  YEAE  IN  SCIENCE  57 

fumes  given  off  from  the  burning  charcoal  ?  To  deter- 
mine this  pour  some  lime  water  into  the  bottle  and 
shake. 

3.  Into  the  deflagrating  spoon  place  some  powdered 
sulphur.    Light  the  sulphur  and  lower  it  into  a  bottle 
of  oxygen.     What  is  the  result?     After  the  sulphur 
has  burned,  smell  the  fumes  in  the  bottle.     What  are 
they?     How  were  they  formed? 

4.  Burn    a    pine    splinter    until    a    good    ember    is 
formed.     Extinguish  the  flame  and  thrust  the  glowing 
ember  into  a  bottle  of  oxygen.     What  happens? 

Does  oxygen  burn?  Does  it  support  combustion?  Is 
it  found  in  the  air?  Why  do  you  think  it  is  or  is  not 
found  in  the  air? 

Summarize  the  properties  of  oxygen  you  have 
learned  from  this  exercise. 

Exercise  32.    Hydrog'en. 

Object:  To  determine  some  of  the  properties  of 
hydrogen. 

Apparatus 

Granulated  zinc  Delivery   tube 

Dilute  hydrochloric  acid  Pneumatic  trough 

Flask  Pine  splinter 

Test  tubes  Large  mouth  bottles 
Thistle  tube 

Directions:  Place  a  handful  of  zinc  in  the  flask. 
Into  the  mouth  of  the  flask  insert  a  rubber  stopper, 
fitted  with  the  thistle  tube  and  the  delivery  tube.  Pour 
enough  hydrochloric  acid  through  the  thistle  tube  into 


58 


LABORATORY  MANUAL 


the  flask  to  cover  the  zinc.     What  action  is  observed? 
This  is  a  chemical  action  between  the  zinc  and  the 


Fig.   20. 

acid.  The  gas  given  off  is  hydrogen.  Allow  the  gas 
to  escape  from  the  delivery  tube  for  a  few  seconds. 
Why?  Fill  a  number  of  bottles  with  hydrogen  by  the 
downward  displacement  of  water.  Keep  the  bottles 
inverted. 

1.  Examine  the  hydrogen  in  one  of  the  bottles.    Has 
it  any  color  ?    Odor  ? 

2.  With  the  mouth  downward,  thrust  into  a  second 
bottle  of  hydrogen  a  lighted  splinter.     What  is  the 
result?    Docs  the  splinter  continue  to  burn?    Does  the 
hydrogen  burn?    If  so,  what  is  the  color  of  the  flame? 
Examine  the  sides  of  the  bottle?     What  do  you  find 
there  ?    Where  did  it  come  from  ?    What  is  the  oxide  of 
hydrogen? 

3.  Allow  a  third  bottle  of  hydrogen  to  stand  mouth 
upward  for  three  minutes.    Then  insert  a  lighted  splin- 
ter.    Is  the  hydrogen  still  there?    Is  hydrogen  lighter 
or  heavier  than  air? 


A  YEAR  IN  SCIENCE  59 

Exercise  33.    Nitrogen. 

Object:  To  determine  some  of  the  properties  of 
nitrogen. 

Apparatus 

Ammonium  chloride  Bunsen  burner 

Sodium   nitrite  Wire  gauze 

Flask  Wide  mouth  bottles 

Rubber  stopper  Glass  plates 

Delivery  tube  Pine  splinter 

Pneumatic  trough  Thistle  tube 
Ring  stand 

Directions :  Place  8  grams  of  sodium  nitrite,  3  grams 
of  ammonium  chloride,  and  15  c.c.  of  water  in  the  flask. 
Into  the  mouth  of  the  flask  insert  a  rubber  stopper, 
fitted  with  a  thistle  tube  and  a  delivery  tube.  Place 
the  flask  on  the  wire  gauze  over  the  Bunsen  flame.  Heat 
gently  and  allow  the  first  gas  to  escape.  Fill  several 
bottles  with  water,  and  invert  them  in  the  water  in  the 
pneumatic  trough.  Fill  the  bottles  with  the  gas  from 
the  flask  by  doAvnward  displacement  of  water.  The 
gas  given  off  is  nitrogen.  Examine  a  bottle  of  nitro- 
gen. Has  it  color?  Odor? 

Into  a  second  bottle  of  nitrogen  insert  a  lighted 
splinter.  Does  the  splinter  continue  to  burn?  Does 
the  nitrogen  burn? 

What  are  the  properties  of  nitrogen? 


60  LABORATORY  MANUAL 

CHAPTER  IX 

ACIDS,  BASES,  AND  NEUTRAL  SUBSTANCES 

Exercise  34.    Acids  and  Bases. 

Object:  To  determine  the  properties  of  acids  and 
bases. 

Apparatus 

Hydrochloric  acid  (dilute)  Red  litmus  paper 

Nitric  acid  (dilute)  Blue  litmus  paper 

.Sodium  hydroxide  Glass  rod 

Ammonium  hydroxide  Beaker 

Directions:  Examine  some  of  the  dilute  hydro- 
chloric acid.  Describe  its  odor.  Dip  the  glass  rod 
into  the  acid  and  touch  it  to  the  tip  of  the  tongue. 
What  is  its  taste  ?  Rub  some  acid  between  the  fingers. 
Describe  its  "feel."  Dip  a  piece  of  red  litmus  paper 
into  the  acid.  What  is  the  effect  of  the  acid  on  the 
paper?  Dip  a  piece  of  the  blue  litmus  into  the  acid. 
What  effect  does  the  acid  have  on  the  blue  paper? 

Apply  the  above  tests  to  the  nitric  acid.  Are  the 
results  the  same  as  those  obtained  with  the  hydro- 
chloric acid?  These  are  methods  commonly  used  to 
detect  any  acid. 

Examine  some  sodium  hydroxide.  Describe  its  odor, 
taste,  "feel,"  using  the  methods  given  in  the  study  of 
acids.  Test  this  substance  with  both  red  and  blue 
litmus  paper.  What  are  the  results?  Examine  ammo- 
nium hydroxide  in  the  same  manner.  How  do  the 
results  compare  with  those  obtained  with  sodium 


A  YEAR  IN  SCIENCE  61 

hydroxide?     These  substances  are  called  bases.     All 
bases  react  similarly  to  these  tests. 

Exercise  35.    Salts  and  Neutralization. 

Object:     A  study  of  neutralization  and  its  results. 

Apparatus 

Hydrochoric  acid    (10%)  Blue  litmus  paper 

Sodium   hydroxide    (10%)  Glass  rod 

Evaporating  dish  Bunsen  burner 
Red  litmus  paper 

Directions:  Pour  one  cubic  centimeter  of  hydro- 
chloric acid  into  the  evaporating  dish.  To  this  add, 
drop  by  drop,  some  sodium  hydroxide.  Stir  constantly 
to  mix  the  liquids.  Test  the  solution  frequently  with 
both  kinds  of  litmus  paper.  If  too  much  sodium 
hydroxide  is  added,  the  solution  will  turn  the  red 
litmus  paper  blue ;  if  too  much  acid  is  present,  the  blue 
litmus  will  turn  red.  Balance  the  solution  by  alternately 
adding  a  few  drops  of  acid  and  base  until  neither 
litmus  paper  is  affected.  When  a  solution  has  no  effect 
on  either  red  or  blue  litmus  paper,  it  is  said  to  be 
neutral.  The  process  of  mixing  an  acid  and  base  to 
produce  a  neutral  substance  is  called  neutralization. 

Over  a  flame  evaporate  the  solution.  Examine  the 
residue.  What  is  its  appearance?  Does  it  taste  like 
any  substance  with  which  you  are  familiar?  This 
product  is  called  a  neutral  salt.  Dissolve  some  of  it  in 
water.  Does  the  solution  have  any  effect  on  litmus 
paper?  What  was  the  substance  evaporated?  What, 
then,  are  the  products  of  neutralization? 


62  LABORATORY  MANUAL 

CHAPTER  X 
WATER  AND  AIR 

Exercise  36.    A  Simple  Electric  Cell.* 
Object:      To   show  how   a   current  of   electricity   is 
produced. 

Apparatus 

Strip  of  amalgamated  zinc,  4x1 

(Strip    of   copper    4x1) 

Two  pieces  of  copper  wire,  each  12  in.  long 
A  block  of  wood  about  4x1x1 
Dilute  sulphuric  acid,  about  5C/C. 
A  compass  or  magnetic  needle 

Note :    On  one  side,  at  the  mid-point  of  the  long  axis 

of  the  block  of  wood,  tack 
the  strip  of  zinc  perpen- 
dicularly with  one  inch  of 
the  zinc  projecting  above 
the  wood  and  two  inches 
extending  below.  On  the 
opposite  side  of  the  wood, 
similarly  fasten  the  strip 
of  copper.  To  the  upper- 
ends  of  the  metallic  strips 
attach  the  copper  wires. 

Directions :       Fill     the 
Flg  21  glass  about  f  full  of  the 

*This  exercise  is  given  here  for  those  teachers  who  wish  to 
present  to  their  classes  some  preliminary  facts  about  electricity 
before  performing  Exercise  37. 


A  YEAE  IN  SCIENCE  63 

sulphuric  acid  solution.  Put  the  block  of  wood  across 
the  tumbler  with  the  free  ends  of  the  metals  dipping 
into  the  acid.  Eecord  what  happens.  Are  there  any  bub- 
bles of  gas  given  off?  From  where  do  they  come? 
Touch  the  free  ends  of  the  copper  wires  to  your  tongue. 
What  effect  do  you  notice  ?  What  is  the  evidence  that 
an  electric  current  is  passing  through  the  wires  ?  Twist 
the  free  ends  of  the  wires  together  and  hold  them  over 
the  compass.  How  is  the  compass  affected?  Is  there 
evidence  of  an  electric  current?  Eecord  all  of  your 
observations.  Find  out  from  some  source  what  is  the 
origin  of  the  electric  current. 

Exercise  37.  Composition  of  Water.  (Demonstra- 
tion.) 

Object:     To  determine  the  composition  of  water. 

Apparatus 

Electrolysis  apparatus  Pine  splinters 

Sulphuric  acid   (5%)  Belljar 

Electric   current 

Directions:  Fill  the  apparatus  with  water  con- 
taining 5%  sulphuric  acid.  When  the  apparatus  is 
almost  filled,  into  each  arm  insert  the  burette,  at  the 
same  time  opening  the  cock  to  drive  out  the  air.  After 
the  burettes  are  completely  filled,  connect  the  positive 
and  negative  poles  of  the  series  with  the  city  current. 
Note  what  happens.  From  what  place  do,  the  bub- 
bles arise  ?  In  which  tube  do  they  form  more  rapidly  ? 

What  is  the   ratio  by  volume  of  .the  ,  gases  int  the 


64 


LABOKATORY  MANUAL 


two  tubes  ?  This  may  be  accurately  obtained  by  taking 
the  readings  on  the  burettes.  When  the  tube  contain- 
ing the  most  gas  is  three-fourths  full,  disconnect  the 
current.  Remove  the  entire  apparatus  into  a  trough 
of  water,  so  that  the  open  ends  of  the 
arms  are  submerged.  Then  remove  each 
burette  separately,  the  one  of  less 
volume  first.  Cover  the  mouth  of  the 
burette  with  the  finger  and  invert. 
Remove  the  finger  and  quickly  insert 
a  lighted  splinter  into  this  gas.  What 
happens?  What  is  this  gas? 

Remove  the  other  burette  in  the  same 
manner  as  the  first.  Hold  the  mouth 
downward  and  insert  a  lighted  splinter. 
What  happens?  What  is  this  gas? 
(See  Exercise  32.) 

Of  what  elements  is  water  composed  ? 
What  proportion  by  volume? 

Exercise  38.    Composition  of  Air. 
Object:     To  determine  the  composi- 
tion of  air. 


Fig.   22. 


Pneumatic  trough 
Belljar 

Evaporating  dish 
Phosphorus 
Lime  water 


Apparatus 

Beaker 
Glass  plate 
Pine  splinter 
Test  tube 
Iron  filings 


Directions:    A.    Fill  the  beaker  with  lime  water  and 


A  YEAR  IN  SCIENCE 


65 


leave  it  exposed  to  the  air  for  48  hours.  At  the  end  of 
that  time  examine  the  appearance  of  the  surface  of  the 
water.  What  does  this  indicate?  What  then  forms  a 
part  of  the  air? 

Does  wood  burn  in  the 
air?  What  element  does 
this  indicate  to  be  present  ? 
How  does  the  burning  of 
a  pine  splinter  in  the  air 
compare  with  the  burning 
in  Exercise  31.  part  4? 
What  does  this  indicate  ? 

Pour  water,  of  room 
temperature,  into  the 
pneumatic  trough.  On  the 
surface  of  the  water  float  the  evaporating  dish  con- 
taining a  piece  of  phosphorus,  the  size  of  a  small  pea. 
Ignite  the  phorphorus  and  cover  quickly  with  the  bell 
jar.  What  is  the  result?  With  what  does  the  phos- 
phorus unite  in  burning?  When  does  it  stop  burning 
in  the  jar?  What  are  the  white  fumes?  Leave  the 
experiment  until  these  fumes  have  been  dissolved  ii? 
the  water.  Does  the  water  rise  in  the  jar?  What  part 
by  volume  does  it  occupy?  This  represents  the 
approximate  proportion  of  oxygen  in  the  air. 

Slip  a  glass  plate  over  the  mouth  of  the  belljar  and 
invert  it.  Examine  the  gas.  Has  it  color?  Odor?  Will 
it  support  combustion?  Does  it  burn?  What  is  this 
gas?  (See  Exercise  33.)  Air  is  a  mixture  of  gases  of 


Fig.    23. 


66  LABORATORY  MANUAL 

which  the  above  are  the  chief  ones.  If  this  experiment- 
is  performed  at  home,  a  small  candle  may  be  lighted 
under  the  belljar  instead  of  phosphorus. 

B.  In  a  test  tube  place  about  a  half  teaspoonful  of 
iron  filings.  Cover  them  with  water.  Then  invert  the 
test  tube  and  allow  the  water  to  run  out  slowly  so  that 
the  filings  will  adhere  to  the  sides  of  the  tube.  Place 
the  mouth  of  the  tube  in  a  beaker  filled  with  water  and 
allow  the  apparatus  to  stand  for  twenty-four  hours. 
At  the  end  of  that  time  measure  the  height  to  which 
the  water  has  risen  in  the  tube.  What  part  of  the  air 
by  volume  did  the  oxygen  occupy?  What  change  has' 
taken  place  in  the  iron  filings?  How  do  the  results  in 
this  experiment  compare  with  those  in  the  one  above? 

CHAPTER  XI 

ATMOSPHERE 

Exercise  39.    Does  Air  Exert  Pressure?     (Demon- 
stration.) 

Object:     To  demonstrate  air  pressure. 

Apparatus 

Oil  can  with  screw  top  Bunsen  burner 

Magdeburg  hemispheres  \Yater 

Air  pump 

Directions :     A.     Screw  the  Magdeburg  hemispheres 

on  to  the  plate  of  the  air  pump  and  open  the  stop-cock. 

'Exhaust  the  air  from  the  hemispheres  and  close  the 


A  YEAE  IN  SCIENCE 


67 


stop-cock.  Try  to  separate  the  hemispheres.  What 
do  you  find?  Open  the  stop-cock  and  try  to  separate 
the  hemispheres.  How  does  this  result  compare  with 
the  result  obtained  in  the  first  instance?  How  do  you 
explain  these  r.esults? 

B.  Fill  the  tin  can  with  water  to  a  depth  of  two 
inches.  With  the  aperture  open,  place  the  apparatus 
over  the  Bunseii  flame  and  heat  until  the  water  boils. 
Tightly  close  the  aperture  and  remove  the  apparatus. 
Let  it  cool  and  note  what  happens.  How  do  you 
explain  the  result? 

Exercise  40.     Barometer.     (Demonstration.) 
Object:    To  study  a  means  of  measuring  atmospheric 
pressure. 

Apparatus 


If! 


Mercury 
Glass  dish 
Torricellian   tube 


Barometer 
Meter  stick 


Directions:  Fill  the  Torricellian 
tube  with  mercury.  Carefully  close 
the  open  end  with  the  thumb  and 
invert  the  tube  into  a  basin  of  mer- 
cury. Remove  the  thumb  from  the 
open  end  of  the  tube  under  the 
mercury  in  the  .basin.  Measure  the 
height  of  the  column  of  mercury  in 
the  tube  above  the  surface  of  the  mercury  in  the 
basin.  What  keeps  the  mercury  in  the  tube?  Would 
the  same  results  be  obtained  if  both  ends  of  the  tube 
\\cre  open? 


Fig.    24. 


68  LABORATORY  MANUAL 

Examine  the  standard  barometer.  How  does  the 
height  of  the  column  of  mercury  in  the  tube  compare 
with  that  of  the  barometer  ?  The  principle  upon  which 
each  is  constructed  is  essentially  the  same.  The  barom- 
eter is  an  instrument  used  for  measuring  atmospheric 
pressure. 

Exercise  41.    Siphon. 

Object:     To  demonstrate  the  action  of  a  siphon. 

Apparatus 

Rubber  tubing  Battery  jars 

Directions:  Fill  a  battery  jar  with  water  and  place 
it  on  top  of  the  desk.  Immerse  a  piece  of  rubber  tubing 
about  3  feet  long  into  the  jar  of  water.  When  the  tube 
is  filled  with  water,  close  one  end  of  the  tube  by 
pinching  between  the  fingers.  Place  a  second  battery 
jar  on  a  chair  or  on  the  floor  below,  but  near,  the  first 
jar.  Quickly  remove  the  closed  end  of  the  rubber  tube 
and  put  it  into  the  lower  vessel.  Release  the  tube. 
What  happens  ?  What  caused  the  water  to  run  ?  How 
long  does  the  water  run?  What  causes  the  water  to 
rise  in  the  first  part  of  the  tube  ?  What  pulls  it  down 
into  the  longer  arm? 

Instead  of  immersing  the  rubber  tube  in  water  to  fill 
it,  place  one  end  in  the  jar  of  water.  Then  suck  the 
air  out  of  the  tube  until  it  is  filled  with  water.  Then 
remove  the  mouth  and  note  the  result. 

Can  you  suggest  any  uses  for  the  siphon? 


A  YEAE  IN  SCIENCE 


69 


Fig.   25. 

Exercise  42.    Convection. 

Object:     To  show  a  method  of  producing  currents 
in  air  and  water. 


Bunsen  burner 
Wire  gauze 

Cotton,  dandelion,  or  milk- 
weed fruits 
King  stand 


Apparatus 

Test  tube 

Water 

Test  tube  holder 

Fine  sawdust 


70  LABORATORY  MANUAL 

Directions:    A.    Convection  of  Gases. 

Place  the  wire  gauze  on  the  ring  stand  and  adjust  a 
low  flame  under  the  gauze.  Over  the  wire  gauze 
drop  very  small  bits  of  cotton  or  the  fruits  of  dande- 
lion or  milk-weed.  Make  a  drawing  indicating  with 
arrows  the  path  taken  by  the  moving  particles.  How 
do  you  explain  this  action? 

B.     Convection  of  Liquids. 

Place  a  small  amount  of  fine  sawdust  in  the  bottom 
of  the  test  tube.  Fill  the  test  tube  three-quarters  full 
of  water.  Adjust  the  Bunsen  burner  for  a  low  flame. 
Hold  the  test  tube  at  a  small  angle  over  the  flame  and 
heat  it  gently  at  one  point  at  the  base.  Note  very 
carefully  the  movements  of  the  sawdust  particles  as 
the  water  becomes  heated.  Make  a  drawing,  indicat- 
ing with  arrows  the  direction  taken  by  the  particles 
in  the  water.  How  do  you  explain  these  movements? 
How  does  this  result  compare  with  that  obtained  with 
gas? 

Convection  is  the  process  by  means  of  which  heat 
is  carried  from  a  hotter  to  a  colder  substance  by  a 
moving  fluid. 

Crystals  of  potassium  permanganate  may  be  used 
effectively  in  place  of  sawdust  to  show  convection  cur- 
rents in  liquids. 

Exercise  43.  Moisture  in  the  Atmosphere — Con- 
densation. 

Object:  To  show  the  presence  of  water- vapor  in  the 
atmosphere. 


A  YEAE  IN  SCIENCE  71 

Apparatus 

Beaker  Glass   plate 

Ice  Bunsen   burner 

Flask 

Directions :  A.  Fill  the  beaker  with  small  pieces  of 
ice  and  water.  Dry  the  surface  of  the  beaker  thor- 
oughly and  set  it  aside,  for  about  five  minutes.  At 
the  end  of  that  time  what  do  you  find  on  the  surface 
of  the  beaker  ?  How  do  you  account  for  it  ? 

B.  Fill  the  flask  half  full  of  water  and  place  it  over 
the  Bunsen  flame.  Heat  the  water  until  it  boils.  Hold 
a  dry  glass  plate  over  the  mouth  of  the  flask.  What 
do  you  find  on  the  plate?  What  is  its  source?  Why 
did  you  use  the  glass  plate  ?.  What  happens,  when  the 
temperature  of  the  atmosphere  is  suddenly  lowered? 

Exercise  44.     Study  of  the  Weather  Map. 
Object:     To  study  the  causes  of  weather  changes. 

Apparatus 

Several  weather  maps  for  each  pupil.  These  maps  should 
include  some  with  well  developed  low  regions  and  some  with 
well  developed  high  areas. 

Directions:  At  the  lower  left  corner  of  the  map  are 
"Explanatory  notes."  Kead  them.  At  the  lower  right 
corner  of  the  map  is  the  "  Wind-barometer  indication. ' r 
Study  this. 

Locate  the  isothermal  and  isobaric  lines.  What  does 
each  mean?  All  barometric  readings  have  been 
reduced  to  what  they  wrould  be  if  the  place  were  at 
sea  level. 


72 


LABOEATOEY  MANUAL 


A  YEAK  IN  SCIENCE 


73 


74  LABORATORY  MANUAL 

Select  a  map  with  a  well  developed  low  region.  This 
low  region  is  called  a  cyclone  or  cyclonic  area.  Using 
the  scale  of  miles  indicated  on  the  map,  find  the  approx- 
imate width  of  this  low  region.  How  many  states  does 
it  cover?  Can  you  tell  in  what  direction  it  is  moving? 
What  is  the  air  pressure  (barometric  reading)  at  the 
center  of  the  low  area  ?  '  How  much  would  the  barom- 
eter rise  in  being  carried  from  the  center  of  the  low  to 
the  outer  isobar  of  the  area?  What  is  the  weather 
condition  over  the  low  region?  Study  the  direction  of 
the  wind  over  the  whole  low  area.  To  what  conclusion 
do  you  come  as  regards  the  direction  of  the  wind  in 
the  low  region?  About  what  is  the  average  wind 
velocity  of  this  area? 

Select  another  map  with  a  well  developed  high  area, 
having  a  number  of  isobars  curving  around  the  word 
high.  This  region  is  called  an  anticyclone  or  anti- 
cyclonic  area.  What  is  the  air  pressure  at  the  center 
of  this  high  area?  How  much  would  a  barometer  fall 
in  being  taken  from  the  center  of  this  high  to  the 
center  of  an  adjacent  low  area  ?  What  is  the  weather 
condition  over  the  high  area?  Study  the  direction  of 
the  wind  over  the  high  region.  What  is  the  difference 
between  the  general  direction  of  the  wind  over  the 
high  and  low  regions? 

What  is  the  general  direction  of  the  movement  of  the 
high  and  low  areas?  Find  out  from  some  source  how 
rapidly  they  move.  Study  the  isothermal  lines.  What 
is  their  general  direction?  What  is  the  lowest  and 


Loi 

„ 


A  YEAE  IN  SCIENCE  75 

highest  temperature  recorded  on  the  map?  What  rela- 
tion does  temperature  have  to  the  high  and  low  area 
regions  ? 

Choose  a  map,  give  its  date,  and  record  for  your 
locality,  the  temperature,  direction  of  the  wind,  veloc- 
ity of  the  wind,  barometer  reading,  state  of  the  sky, 
and  kind  of  precipitation,  if  any. 

CHAPTER  XII 

SOILS 

Exercise  45.    Water  Capacity  of  Soils. 

Object:      To   determine   the   capacity  for   water   of 

different  soils. 

Apparatus 

Sand  Leaf-mold 

Clay  Tin  cans 

Loam  Balance  and  weights 

Directions:  Expose  the  different  soils  used  in  this 
ercise  to  the  room  air  for  a  period  of  two  days. 
At  the  end  of  that  time  find  the  weight  of  the  can. 
The  can  should  have  a  number  of  holes  in  the  bottom. 
Fill  the  can  two  thirds  full  of  the  air  dried  sand,  and 
find  the  weight  of  both  the  can  and  the  sand.  Then 
compute  the  weight  of  the  sand.  Thoroughly  saturate 
the  sand  with  water  and  set  it  aside  for  about  two 
hours.  Again  weigh  the  can  with  its  contents.  From 
this  result  subtract  the  weight  of  the  can  and  dry 
soil.  The  difference  represents  the  amount  of  water, 


76 


LABORATORY  MANUAL 


by  weight,  which  the  sand  is  capable  of  holding.  What 
per  cent  of  the  weight  of  the  sand  is  the  weight  of  the 
water  ? 

Eepeat  the  above  experiment  for  each  of  the  soils: 
clay,  loam,  and  leaf -mold,  or  any  combination  of  soils 
suggested  by  the  instructor. 

Is  the  water  capacity  the  same  for  all  soils?'  Which 
holds  the  most?  Which  the  least? 

Record  results  as  follows : 


Sand 

Clay 

Loam 

Leaf- 
mold 

Sand 
and 
Leaf- 
mold 

Clay 
and 
Leaf- 
mold 

Weight  of  can 
Weight  of  can  and 
dried  soil 
Weight  of  dry  soil 
(  calculated  ) 
Weight  of  both 
with  water 
Weight  of  water 
(  calculated  ) 
Water  capacity  in 
per  cent. 

Exercise  46.    Soil  Solutions. 

Object:     To    determine    whether    water    in    passing 
through  the  soil  dissolves  mineral  substances. 

Apparatus 

Slips  of  Wandering  Jew 


Evaporating   dishes 
Bunsen  burner 
Well  water 
Rain  water 


Flasks 
Ring  stand 


Directions:     A.     Place  50  c.c.  of  well  water  in  one 
evaporating  dish  and  the  same  amount  of  rain  water, 


A  YEAE  IN  SCIENCE  77 

or  distilled  water,  in  another.  Evaporate  the  water  in 
each  dish  over  the  Bunsen  flame.  What  is  left  in 
each  case  ?  How  do  you  account  for  the  difference  ? 

B.     In  which  kind  of  water  do  plants  grow  best? 

Fill  one  flask  with  well  water  and  another  with  rain, 
or  distilled  water.  In  each  flask  place  "slips"  of 
Wandering  Jew  of  about  the  same  size.  Change  the 
water  in  the  flasks  two  or  three  times  a  week  for 
about  a  month.  In  which  do  the  plants  grow  best? 
What  is  the  explanation? 

CHAPTER  XIII 

PLANTS  DEPENDENT  UPON  AIR  AND  MOISTURE 

Exercise  47.     Gross  Structure  of  Leaves. 
Object:     To  study  the  parts  of  a  leaf. 

Apparatus 

Lilac  leaves  Lily-of-the-valley   leaves 

Directions :     A.     Parts. 

Carefully  examine  a  lilac  leaf.  Make  a  drawing 
of  the  leaf.  Label  the  broad  expanded  portion,  the 
Made,  and  the  stem  by  which  it  was  attached,  the 
petiole.  Compare  the  lengths  of  the  petioles  on  a  num- 
ber of  leaves  on  a  lilac  branch.  From  this  observation 
what  is  one  of  the  functions  of  the  petiole?  The  sur- 
face of  the  leaf  is  provided  with  small  openings  or 
pores,  called  stomates,  through  which  the  leaf  respires. 


78  LABORATORY  MANUAL 

At  the  discretion  of  the  instructor  these  may  be  shown 
under  the  microscope. 

B.    Venation. 

Examine  the  lilac  leaf  again.  Note  the  continuation 
of  the  petiole  through  the  blade.  This  is  called  the 
mid-rib,  and  its  branches,  the  veins.  Compare  the 
arrangement  of  the  veins  in  the  leaves  of  any  lily  with 
that  of  the  lilac  leaf.  How  do  they  differ?  These  are 
examples  of  the  two  kinds  of  venation.  Make  a  draw- 
ing of  each  and.  label  the  lilac  leaf,  netted  veined,  and 
the  lily  leaf,  parallel  veined. 

Exercise  48.     Chloroplasts. 

Object:  To  study  the  organs  which  contain  the 
green  coloring  matter  of  plants. 

Apparatus 

Moss  or  Elodea  leaves  Scalpel 

Glass  slides  Compound  microscope 

Cover  glasses 

Directions:  Place  a  drop  of  water  on  the  center  of 
a  glass  slide.  In  this  put  a  leaf  of  elodea  or  moss  and 
cover  it  with  the  thin  glass  cover.  Examine  this  very 
carefully  under  the  low  power  of  the  microscope.  Note 
the  oblong  parts  of  which  the  leaf  is  composed. 
Each  of  these  parts  is  a  cell.  Examine  one  of 
these  carefully.  What  is  its  shape?  What  is  the 
appearance  of  the  wall,  cell  wall,  surrounding  it? 
Within  the  cell  note  the  many  small  bodies,  green  in 
color.  What  is  their  shape  ?  How  many  are  there  in  a 


A  YEAE  IN  SCIENCE  79 

cell?  What  is  their  arrangement?  These  small  bodies 
contain  a  green  substance  known  as  chlorophyll  and 
for  that  reason  they  are  called  chloroplasts  (chloro 
menus  green;  plattein,  to  form).  Within  the  cell  there 
is  an  almost  colorless,  jelly-like  substance  known  as 
protoplasm.  This  is  the  living  part  of  the  cell.  It  is 
somewhat  granular  in  appearance.  Upon  careful  exam- 
ination you  may  be  able  to  see  it. 

Exercise  49.    Making  of  Food  for  Plants. 
Object:     The  relation  of  chlorophyll  to  starch  forma- 
tion. 

Apparatus 

Variegated  ^cranium  Iodine 

Alcohol  Beaker 

Bunsen  burner  Evaporating  dish 

Corn  starch 

Directions:  Place  a  small  amount  of  corn  starch  in 
an  evaporating  dish  and  pour  a  drop  of  iodine  over  it. 
What  color  does  the  starch  turn?  If,  when  iodine  is 
placed  on  a  substance,  its  color  turns  to  a  blue-black, 
starch  is  present. 

Place  a  geranium  with  variegated  colored  leaves  in 
the  bright  sunlight  for  the  greater  portion  of  a  day. 
Select  a  few  leaves  on  the  plant  and  sketch  the  blades 
to  show  the  color  patterns  on  them.  Remove  these 
leaves  and  immerse  them  immediately  into  boiling 
water  to  kill  them.  After  five  minutes  boiling,  place 
the  leaves  in  a  vessel  of  96%  alcohol  to  extract  the 
chlorophyll.  When  the  leaves  become  white,  spread 


80  LABOEATOKY  MANUAL 

them  on  a  white  surface  and  cover  them  with  a  weak 
solution  of  iodine.  In  what  part  of  the  leaf  is  starch 
found?  Has  chlorophyll  anything  to  do  with  starch 
formation  ? 

Exercise  50.    Making  of  Food  for  Plants,  continued. 
Object:     To  determine  the  relation  of  sunlight  to 
starch  formation. 

Apparatus 

Nasturtium  Iodine 

Alcohol  Beaker 

Bunsen  burner  Evaporating  dish 
Corn  starch 

Directions:  Place  a  nasturtium  plant  in  the  bright 
sunlight  and  another  in  a  dark  room.  On  the  after- 
noon of  the  second  day  remove  several  leaves  from  each 
plant,  being  careful  to  keep  the  two  sets  of  leaves 
separate.  Kill  them  and  extract  the  chlorophyll  in  the 
same  manner  as  directed  in  the  preceding  exercise. 
Place  the  leaves  on  a  white  surface  and  test  each  for 
the  presence  of  starch.  Is  starch  found  in  both  sets  of 
leaves?  What  does  this  indicate  concerning  the  rela- 
tion of  sunlight  to  starch  making  ? 

Exercise  51.    By-Products  in  Food  Making. 
Object:     To  determine  the  gas  given  off  when  plants 
make  starch. 

Apparatus 

Green  water  plants  Funnel 

Mushrooms  Test  tube 

Glass  jar  Pine  splinter 


A  YEAE  IN  SCIENCE 


81 


Directions:  Place  some  green  water  plants  under  a 
funnel  in  clear  water,  as  in  Figure  28.  Place  the  jar 
in  sunlight  for  several  days,  and 
allow  any  escaping  gas  to  collect  in 
a  test  tube  placed  over  the  stem  end 
of  the  funnel.  When  there  is  an 
inch  or  more  of  gas  in  the  test  tube, 
remove  the  tube  from  over  the  fun- 
nel, being  careful  not  to  take  it  out 
of  the  water  in  the  jar.  After  closing 
the  mouth  of  the  tube  with  the 
thumb,  remove  it  from  the  jar  of 
water.  Invert  the  tube,  then  remove  Fis"-  28< 

the  thumb  and  quickly  thrust  a  glowing  pine  splinter 
into  the  gas  in  the  tube.  What  is  the  result?  What 
gas  does  this  indicate  is  present? 

Repeat  the  same  experiment,  using  mushrooms  in 
place  of  the  green  plants.  What  result  do  you  obtain 
this  time?  How  do  you  account  for  the  difference 
between  this  result  and  the  one  obtained  with  the 
green  plants? 

Exercise  52.    Transpiration. 

Object:  To  show  that  the  excess  water  in  plants 
is  given  off  by  the  leaves. 


Glass  tumblers 
Card  board 


Apparatus 

Paraffin 
Geranium 


Directions:     Cut  off  a  small  branch  of  geranium. 
Place  the  cut  end  of  it  through  a  hole  in  a  piece  of 


82 


LABORATORY  MANUAL 


cardboard.  Fill  one  tumbler  with  water  and  place 
the  cardboard  over  it,  with  the  cut  end  of  the  geranium 
extending  into  the  water.  Paraffin  the 
entire  upper  surface  of  the  cardboard 
to  prevent  any  evaporation  of  water 
through  it  or  around  the  stem  of  the 
geranium.  Over  the  leaves  of  the 
geranium  invert  the  second  tumbler 
and  set  the  experiment  aside  for  a  few 
hours.  Then  examine  the  inside  of  the 
upper  tumbler.  How  do  you  account 
for  the  condition  found  ? 


Fig.   29. 


Exercise  53.    Rate  of  Transpiration. 
Object:     To  determine  the  difference  in  the  rates  of 
loss  of  water  in  different  plants. 


Cobalt  paper 
Rubber    plant 
Nasturtium 


Apparatus 

Scissors 
Paper  clips 


Directions:  Cobalt  paper  is  prepared  by  saturating 
filter  paper  in  a  solution  of  cobalt  chloride.  The  paper 
is  then  thoroughly  dried  in  an  oven.  What  is  the  color 
of  the  paper?  On  a  small  piece  of  paper  place  a  drop 
of  water.  What  happens  ?  Cut  several  pieces  of  paper, 
each  about  one  inch  square.  With  a  clip  fasten  one 
piece  on  the  upper,  and  another  piece  on  the  under 
surface  of  a  leaf  of  a  rubber  plant.  Note  the  exact 
time  that  this  is  done.  Watch  the  paper.  What  change 
do  you  observe?  How  long  did  it  take  to  produce  this 


A  YEAR  IN  SCIENCE  33 

change  ?  What  causes  it  ?  Do  the  papers  on  the  upper 
and  lower  surfaces  change  at  the  same  time?  What 
does  this  indicate?  Repeat  this  experiment  on  leaves 
of  the  nasturtium  and  of  several  other  plants.  At 
what  rate  do  you  find  water  is  given  off  from  their 
leaves?  Do  all  plants  transpire  at  the  same  rate? 

Exercise  54.    Is  Air  Necessary? 
Object:     To  determine  whether  air  is  necessary  for 
the  growth  of  plants. 

Apparatus 

Wide  mouth  bottles  Paraffin 

Kubber  stoppers  Glass   plate 

Seeds   (well  soaked)  Bell  jar 

Geranium    plant  Blotting  paper 

Directions:  A.  Place  blotting  paper  to  the  depth 
of  an  inch  in  the  bottom  of  each  of  two  wide  mouth 
bottles.  Saturate  the  paper  thoroughly  with  water. 
Fill  each  bottle  three-fourths  full  of  soaked  pea  seeds. 
Close  one  bottle  tightly  with  a  rubber  stopper  to 
exclude  the  air  and  leave  the  second  bottle  open  to 
the  air.  Place  the  two  bottles  under  the  same  condi- 
tions of  temperature  and  light.  Make  and  record  daily 
observations  for  one  week  on  the  growth  of  the  seeds 
in  the  bottles.  What  do  you  conclude  from  the  results? 

B.  Do  other  forms  of  plant  life  require  air?  To 
determine  this  select  two  potted  plants  of  equal  size. 
Water  both  plants  thoroughly  and  place  one  under 
a  belljar.  Make  this  air-tight  by  sealing  the  open 
end  of  the  belljar  to  a  glass  plate.  Now  place  the 


84  LABORATORY  MANUAL 

two  plants  under  the  same  conditions  of  light,  moisture, 
and  temperature.  Do  not  change  these  conditions  until 
the  experiment  is  completed. 

Note  and  record  results  as  you  did  with  the  seeds. 
At  the  end  of  a  week  do  you  notice  any  differences  in 
the  two  plants?  What  does  this  indicate? 

Exercise  55.    Exchange  of  Gases  in  Respiration. 
Object:     To  determine  the  gases  exchanged  in  res- 
piration of  plants. 

Apparatus 

Wide  mouth  bottles  Pine  splinter 

Green  plants  Stoppers 

Lime  water 

Directions:  Fill  three  bottles  to  the  depth  of  one- 
half  inch  with  water.  Into  two  of  the  bottles  place 
a  few  shoots  of  green  plants.  Close  the  three  bottles 
tightly  with  rubber  stoppers  and  place  them  in  a 
dark  room  until  the  next  recitation.  What  gas  was  in 
the  bottles  when  the  experiment  was  set  up?  Is  this 
same  gas  present  in  the  bottles  containing  the  green 
plants  at  the  end  of  the  experiment?  In  the  bottle 
without  plants?  To  determine  this,  insert  into  one  of 
the  bottles  with  plants  a  lighted  splinter.  What  is  the 
result?  In  the  same  manner  insert  a  lighted  splinter 
into  the  bottle  having  no  plants.  What  is  the  result? 
What  do  these  results  indicate?  Test  the  gas  in  the 
third  bottle  with  lime  water.  What  is  the  effect  ?  From 
these  results  what  gases  are  exchanged  in  respiration 
of  plants? 


A  YEAB  IN  SCIENCE  §5 

Exercise  56.    Roots. 

Object:    A  study  of  the  kinds  and  functions  of  roots. 

Apparatus 

Lupine   seedlings  Carrot 

Wheat  seedlings  Dahlia  roots 

Directions:  Examine  the  root  of  a  lupine.  Is  there 
a  single  branch,  or  are  there  several  of  equal  size  arising 
from  the  same  point?  These  are  called  the  primary 
roots.  The  roots  growing  from  the  primary  are  called 
the  secondary  roots.  Have  they  any  definite  arrange- 
ment on  the  single  primary  root  of  the  lupine?  At 
what  angle  do  they  grow  from  the  main  root?  What 
function  of  the  root  does  this  suggest?  With  the 
lupine  compare  a  carrot,  radish,  beet,  or  dandelion  root. 
How  do  the  latter  differ  from  the  lupine?  What  other 
function  does  this  suggest  for  some  roots  ? 

Examine  the  roots  of  some  grain  seedlings.  Do  they 
have  a  single  primary  root  or  many  fibrous  roots? 
Make  observations  similar  to  those  made  on  the  lupine 
root.  What  difference  do  you  observe?  Compare  the 
dahlia  root  with  those  of  any  grain.  There  are  two 
principal  kinds  of  underground  roots.  Those  growing 
with  a  single  main  branch  are  called  primary  tap  roots, 
while  those  with  several  main  branches  are  called  mul- 
tiple primary  or  fibrous  roots.  An  example  of  the  tap 
root  is  the  lupine ;  of  the  fibrous  roots,  the  grains. 
When  the  tap  root  is  used  for  food  storage  as  in  the 
radish,  it  is  called  a  fleshy  tap  root.  When  the  fibrous 


§6  LABOEATOEY  MANUAL 

roots  store  food,  as  in  the  dahlia,  we  have  the  fleshy 
fibrous  or  fascicled  roots.  Sketch  one  of  each  of  the 
above  kinds  of  roots. 

Exercise  57.    Roots  as  Orguns  of  Absorption. 
Object :     To  study  root  hairs  and  the  path  of  liquids 
through  the  root. 

Apparatus 

Petri   dishes  Carrot 

Blotting  paper  Eosin  solution 

Eadish  seeds 

Directions :  A.  Line  the  bottom  of  a  petri  dish  with 
blotting  paper.  Moisten  it  thoroughly  and  scatter  over 
it  a  half  dozen  radish  seeds.  Cover  and  set  aside  for 
forty-eight  hours.  At  the  end  of  that  time  examine 
the  roots  which  have  been  formed.  The  fine  hair-like 
growths  found  along  the  surface  are  called  root  hairs. 
Are  they  found  on  all  parts  of  the  root?  What  is  the 
condition  of  the  tip  of  the  root  ?  The  little  yellow 
portion  over  the  tip  of  the  root  is  the  root  cap  which 
protects  the  delicate  portion  of  the  root  tip. 

Make  an  accurate  drawing  showing  root  hairs  and 
root  cap. 

The  mineral  foods  for  plants  are  dissolved  in  the  soil 
water.  These  substances  enter  the  roots  by  diffusion 
through  the  root  hairs. 

B.  Make  a  longitudinal  section  of  a  carrot  or  any 
other  good  tap  root.  How  many  different  regions  do  you 
distinguish?  The  central  portion  is  the  woody  part, 
outside  of  which  is  the  cortex.  Surrounding  the  whole 


A  YEAE  IN  SCIENCE  87 

is  a  thin  skin,  the  epidermis,  one  layer  of  cells  thick. 
Make  a  cross  section  of  the  carrot  and  identify  the 
parts.  Make  a  drawing  of  both  the  cross  and  the 
longitudinal  sections. 

To  determine  the  paths  of  liquids  through  roots, 
place  the  cut  end  of  a  carrot  in  eosin  solution  for  a 
number  of  hours.  Make  a  cross  section  and  examine. 
Indicate  in  the  drawing  of  the  cross  section  the  region 
through  which  the  liquid  passed. 

Exercise  58.     External  Structure  of  Stems. 
Object:    ,To  study  the   external  characteristics   of 

stems. 

Apparatus 

Box  elder  twi«;s  Dissecting  microscope 

Scalpel 

Directions:  Procure  a  twig  of  box  elder  about  two 
feet  in  length.  Examine  it  carefully,  noting  the  gen- 
eral characteristics  of  the  bark.  At  intervals  on  the 
twig  notice  the  small  blister-like  elevations,  the  lenti- 
cels.  These  are  openings  through  the  bark  of  young 
stems  for  the  interchange  of  gases.  On  a  twig  of  this 
season's  growth,  how  are  the  leaves  arranged?  On 
the  older  portions  of  the  stem  note  the  leaf  scars.  Do 
you  find  any  buds  on  the  stem  ?  What  relation  do  they 
bear  to  the  leaves  or  to  the  leaf  scars?  Do  you  find 
rings  of  narrow  scars  on  the  stem?  What  difference 
in  the  appearance  of  the  stem  above  and  below  these 
rings?  Prom  what  were  these  rings  of  scars  caused? 


88  LABOKATORY  MANUAL 

How  would  you  determine  the  age  of  the  branch  from 
the  external  markings?  From  the  external  structure, 
how  would  you  distinguish  a  stem  from  a  root  ?  Draw 
a  twig  to  show  the  above  mentioned  parts. 

Exercise  59.    Internal  Structure  of  Stems. 
Object:     To  study  the  internal  structure  of  stems. 

Apparatus 

Box  elder  twigs  Scalpel 

Corn  stems  Dissecting    microscope 

Directions :  A.  Corn  Stem :  Take  an  internode  of  an 
old  corn  stalk.  Note  on  the  cut  end  the  outer  rind 
surrounding  the  pith.  Throughout  the  pith  note  the 
small  dots  of  woody  substance.  Break  the  stalk  into 
two  parts.  What  do  you  find  the  small  dots  to  be? 
Cut  a  longitudinal  section  and  follow  a  few  of  the 
small  fibres.  Do  they  pass  the  length  of  the  internode  ? 
Through  the  node  into  the  next  internode?  These 
thread-like  fibres  are  called  fibro-vascular  bundles. 
Make  a  drawing  showing  these  points.  Under  the  lens 
of  the  dissecting  microscope  examine  a  cross  section 
of  the  corn  stem.  Are  the  bundles  regularly  arranged  ? 
Where  are  they  most  numerous,  near  the  margin  or 
toward  the  center?  Can  you  determine  of  what  the 
rind  is  composed?  Make  a  drawing  to  show  these 
points. 

B.  Box  Elder  Stem :  Make  a  longitudinal  section  of  a 
small  piece  of  box  elder  stem.  How  many  parts  do  you 
distinguish?  Where  is  the  wood  in  this  stem  in  refer- 


A  YEAR  IN  SCIENCE  89 

once  to  the  pith?  In  a  cross  section  of  the  stem,  locate 
the  parts  seen  in  the  longitudinal  section.  Note  the 
lines  running  through  the  wood  from  the  pith  to  the 
hark.  These  lines  of  pith  are  called  medullary  rays. 
How  does  the  arrangement  of  the  wood  in  the  box 
elder  stem  differ  from  that  in  the  corn  stem?  Make 
a  drawing  of  both  the  longitudinal  and  cross  section 
of  the  box  elder,  and  label  the  parts.  These  stems  are 
examples  each  of  the  two  classes  of  stems  of  flowering 
plants.  The  corn  stalk  is  an  example  of  the  monocoty- 
ledenous  type,  and  the  box  elder  of  the  dicotyledenous 
type. 

Exercise  60.    Functions  of  Stems. 

Object :     To  determine  one  of  the  functions  of  stems. 

Apparatus 

Impatiens   stem  Beaker 

Eosin  solution  Scalpel 

Potato 

Directions:  Cut  off  a  number  of  branches  of  the 
Impatiens,  of  the  Coleus,  or  of  any  other  plant  with  a 
thin  epidermis,  and  immediately  place  the  cut  end  in  a 
beaker  of  eosin  solution.  Similarly,  cut  off  the  end  of 
a  potato  and  place  the  cut  end  in  the  eosin  solution. 
Set  them  aside  for  several  hours.  Then  examine  the 
stems  to  determine  the  paths  taken  by  the  red  solu- 
tion. To  see  this  more  clearly,  make  a  longitudinal 
section  of  the  stem.  What  part  of  the  stem  is  stained, 
the  pith,  wood,  or  epidermis?  Does  this  stain  extend 
into  the  leaves  ?  What  is  its  course  through  the  leaves  ? 


90  LABOKATOEY  MANUAL 

Break  off  a  leaf  from  the  stem.  Examine  the  end  of 
the  leaf  stalk.  What  do  the  red  dots  on  the  end  indi- 
cate ?  Through  Avhat  part  of  the  stem  do  liquids  pass  ? 
Make  a  drawing  of  a  cross  section  of  a  stem  to  show 
the  path  of  liquids.  From  general  observations  can 
you  suggest  other  functions  of  stems? 

CHAPTER  XIV 

FLOWERS  AND  SEEDS 

Exercise  61.    A  Typical  Flower. 

Object:     To  learn  the  parts  of  a  typical  flower. 

Apparatus 

Trillium  Forceps 

Dissecting  microscope  Needles 

Scalpel 

Directions:  Carefully  examine  the  flower  of  the 
trillium.  Note  the  outer  circle  or  whorl  of  leaf-like 
parts.  How  many  are  there?  What  is  their  size  and 
shape  ?  Each  of  these  parts  is  called  a  sepal;  together 
they  form  the  calyx.  The  second  whorl  of  parts  forms 
the  corolla,  each  separate  part  being  a  petal. 

How  many  petals  are  there  ?  How  are  they  arranged 
on  the  flower  stalk  in  reference  to  the  sepals?  How 
do  they  compare  in  size  and  number  to  the  sepals? 
What  is  the  nature  of  the  parts  of  the  third  cycle  of 
floral  parts  just  inside  of  the  corolla?  These  are  the 
stamens.  How  many  are  there?  How  are  they 
arranged?  Remove  a  stamen  and  note  the  slender 


A  YEAR  IN  SCIENCE  91 

stalk,  the  filament,  with  the  enlarged  end,  the  anther. 
On  a  mature  anther  note  the  powdery  substance,  the 
lH)lh-n.  Make  a  drawing  of  a  stamen  showing  these 
parts. 

In  the  center  of  the  flower  is  the  pistil.  The  large 
bulbous  base  is  the  ovary  and  the  three  parted  pro- 
jection above  is  the  stigma.  Examine  the  stigma  care- 
fully. Is  its  upper  surface  smooth  or  rough?  Make 
a  drawing  of  the  pistil  and  label  the  parts.  Make  a 
cross  section  of  the  ovary.  How  many  compartments 
do  you  find  in  the  ovary?  How  many  rows  of  seeds  in 
each  compartment?  Where  are  they  attached?  Draw 
a  cross  section  of  the  ovary.  Make  a  diagram  of  the 
flower  showing  its  parts  and  their  relation  to  each 
other.  Examine  a  number  of  other  flowers  to  acquaint 
yourself  with  the  floral  parts. 

Exercise  62.     Structure  of  Seeds. 
Object:     To  study  the  structure  and  parts  of  seeds. 
Apparatus 

Scalpel  Lima  beans  (soaked) 

Needles  Castor  beans   (soaked) 

Dissecting  microscope  Corn   (soaked) 

Directions : 

A.     Lima  Bean. 

(a)  External  structure.  Examine  a  lima  bean. 
What  is  its  color,  size,  shape?  What  are  the  charac- 
teristics of  the  outer  coating,  the  testa  of  the  seed? 
Note  the  scar,  the  Jiilum,  on  the  concave  side  of  the 
seed.  How  was  this  formed?  At  one  end  of  the 


92  LABORATORY  MANUAL 

hilum,  locate  a  small  opening,  the  micropyle.  Draw 
the  bean  from  the  side,  and  from  the  edge.  Label  the 
parts. 

(b)  Internal  structure.  With  the  scalpel  carefully 
open  the  seed  by  cutting  through  the  testa  along  the 
convex  side.  Again  examine  the  testa.  Within,  the 
testa  notice  the  embryo  plant  consisting  of : 

(1)  the  cotyledons,  two  large  seed  leaves.    Are  these 
joined?    Where? 

(2)  the  plumule,  the  small  rudimentary  leaves  be- 
tween the  cotyledons ; 

(3)  the  hypocotyl,  the  rudimentary  stem  and  root. 
Draw   one   of  the   cotyledons   showing  the   plumule 

and  the  hypocotyl  in  position,  labeling  parts. 

B.     Corn. 

In  the  bean,  the  entire  contents  of  the  seed  consist 
of  the  embryo ;  but  this  is  not  always  the  case.  Often, 
as  in  corn,  food  is  stored  in  a  part  called  the  endosperm. 

(a)  External  structure.    Examine  a  kernel  of  corn. 
Note  the  outer  covering ;  also  notice  the  groove  where 
the  embryo  lies.     The  hilum  and  micropyle  are  at  the 
small  end  of  the  kernel.     Draw  the  flat  side  of  the 
kernel  showing  the  position  of  the  embryo. 

(b)  Internal  structure.    Remove  the  skin.    Cut  the 
kernel  lengthwise,  perpendicular  to  the  flat  surface. 
Most  of  the  outside  of  the  kernel  consists  of  a  white 
flowery  substance,  the  endosperm.    Of  what  use  is  this? 
Find  the  embryo.  Locate  the  plumule,  radicle,  or  root, 
and  the  cotyledon.     Compare  each  of  these  parts  with 


A  YEAR  IN  SCIENCE 


93 


corresponding  parts  in  the  bean.  Draw  a  longitudinal 
section  of  the  corn,  showing  and  labeling  the  coty- 
ledon, plumule,  radicle,  and  endosperm. 

C.     Castor  bean. 

Compare  the  parts  of  the  castor  bean  with  those  of 
the  lima  bean  and  corn. 

Exercise  63.     Seed  Dispersal. 

Object:  To  see  how  seeds  are  adapted  for  the  pur- 
pose of  distribution. 

Apparatus 

The  available  seeds  and  fruits  of  your  locality 

Directions:  Seeds  are  scattered  in  various  ways  by 
wind,  water,  animals,  and  by  some  contrivance  for 
forcibly  expelling  the  seeds.  Examine  the  seeds  and 
fruits  supplied  you,  and  classify  each  according  to  its 
means  of  distribution  as  follows : 


Seed  or  Fruit 

Wind 

W7ater 

Animal 

Other 
Methods 

How 

Adapted 

Dandelion 
Stick-tights 
Burdock 
Wild-cherry 
Mi  Ik  wood 
Wild    geranium 
Morning-glory 
Impatiens 

Exercise  64.     Conditions  for  Germination. 

Object:  To  determine  the  best  conditions  of  tem- 
perature, moisture,  and  air  supply  for  the  germination 
of  seeds. 


94 


LABORATORY  MANUAL 


Apparatus 


Wide  mouth  bottles 
Rubber    stoppers 
Blotting  paper 
Thermometer 


Soaked  seeds,  peas,  corn,  etc. 

Refrigerator 

Oven 


Directions:  A.  Relation  of  temperature  to  germi- 
nation. 

In  the  bottom  of  each  of  the  four  wide  mouth  bot- 
tles, place  several  layers  of  thoroughly  moistened 
blotting  paper.  In  each  bottle  put  twelve  soaked  pea 
seeds.  With  the  conditions  of  moisture,  light,  and  air- 
supply  the  same  for  all  bottles,  place  them  in  different 
but  fairly  constant  temperatures.  Place : 

1.  the  first  bottle  on  the  ice  in  the  refrigerator ; 

2.  the  second  bottle  on  the  shelf  in  the  refrigerator ; 

3.  the  third  bottle  in  the  room ; 

4.  the  fourth  in  an  oven  at  a  temperature  of  100°  F. 
With  a  thermometer  obtain  and  record  the  exact 

temperature   in   each  instance.     Make  daily  observa- 
tions for  a  week,  tabulating  your  results  as  follows : 


Bottle 

Temp. 

24  hrs. 

48  hrs. 

72  hrs. 

96  hrs. 

120  hrs. 

A, 

A2 

A:t 

A4 

What  do  you  conclude  from  the  above  experiment 
is  the  best  temperature  for  the  germination  of  peas? 
B.     Relation  of  moisture  to  germination. 
Place  seeds  in  four  wide  mouth  bottles  as  follows: 


A  YEAR  IN  SCIENCE  95 

1.  twelve  dry  seeds  in  a  bottle  in  which  there  are 
several  layers  of  barely  moistened  blotting  paper; 

2.  twelve    soaked    seeds    in    a    bottle    with   barely 
moistened  paper ; 

3.  twelve  soaked  seeds  in  a  bottle  with  thoroughly 
wet  paper ; 

4.  twelve  soaked  seeds  in  a  bottle  and  almost  cover 
them  with  water. 

Place  these  bottles  aside  under  similar  conditions  of 
temperature,  light,  and  air  supply.  Make  daily  obser- 
vations for  a  week  and  tabulate  results  as  above.  What 
do  you  conclude  from  this  experiment? 

C.     Relation  of  air  supply  to  growth. 

Place  several  layers  of  blotting  paper  in  each  of 
two  bottles.  Moisten  the  paper  thoroughly.  Fill  each 
bottle  one-third  full  of  soaked  seeds.  Cork  one  of  the 
bottles  tightly  making  it  air  tight,  and  leave  the  other 
open.  With  all  other  conditions  the  same,  set  the 
bottles  aside.  At  the  end  of  48  hours  examine  the 
seeds  in  each  bottle  and  record  results.  Is  air  neces- 
sary for  the  germination  of  seeds? 

Exercise  65.    Seedlings.  * 

Object:    A  general  study  of  seedlings. 


Apparatus 

Wide  mouth  bottle  Seedlings,   peas,   corn,   etc. 

Mosquito  netting  Scalpel 

Directions:     A.     Make   observations   on   a   number 


96  LABORATORY  MANUAL 

of  seeds  just  beginning  to  sprout.  Review  the  parts 
of  the  embryo  in  Exercise  62.  What  part  of  the 
embryo  emerges  first  from  the  seed  coat?  At  what 
point  does  it  come  through?  Into  what  part  of  the 
mature  plant  does  it  develop?  Make  a  sketch  to  show 
these  points. 

B.  To  determine  one  of  the  functions  of  a  cotyledon, 
set  up  the  following  experiment : 

Fill  a  wide  mouth  bottle  with  water.  Cover  the 
mouth  of  the  bottle  with  mosquito  netting.  Choose 
four  young  seedlings  of  about  the  same  size  each  of 
corn,  pea,  and  lupine.  From  two  of  each  kind  care- 
fully remove  the  cotyledons.  Then  suspend  all  the 
seedlings  from  the  netting  with  the  roots  projecting 
into  the  water.  After  a  week  make  observations  on 
the  growth  of  the  seedlings  with  cotyledons,  and  com- 
pare with  the  growth  of  those  from  which  the  coty- 
ledons were  removed. 

C.  Methods  of  emerging  from  the  soil. 

In  a  pot  of  germinating  seeds  of  the  castor  bean, 
squash  or  lima  bean,  and  corn,  or  any  other  grain, 
make  observations  on  various  stages  of  the  growth  of 
the  seedlings.  In  the  castor  bean,  squash,  or  lima  bean, 
what  part  of  the  seedling  emerges  from  the  soil  first? 
In  what  manner  does  it  come  above  the  surface?  Of 
what  advantage  is  this  method  to  the  seedling?  Does 
the  arch  persist  after  the  cotyledons  and  plumule  are 
above  the  surface  ? 

Sketch  at  least  three  stages  in  the  above  develop- 


A  YEAE  IN  SCIENCE  97 

ment.  Make  similar  observations  on  the  corn.  In  what 
manner  does  it  send  its  shoot  through  the  soil  ?  Sketch. 
Examine  a  number  of  other  seedlings  and  place  them 
under  the  proper  one  of  the  above  classes. 

D.  The  growth  above  the  ground  is  called  the 
shoot  (stem  and  leaves),  while  that  below  is  the  root. 
The  points  on  the  stem  from  which  the  leaves  grow 
are  called  nodes.  The  portion  of  the  stem  between 
two  nodes  is  the  internode.  Sketch  a  pea  seedling  to 
show  nodes  and  internodes. 

Examine  well  grown  seedlings  of  peas  and  beans.  In 
each  instance  where  are  the  cotyledons,  above  or 
below  the  surface  of  the  soil?  What  is  their  present 
condition?  What  does  this  indicate  as  to  the  function 
of  the  cotyledons?  What  change  has  the  plumule 
undergone?  Is  there  a  new  plumule?  Sketch  to  show 
the  above  points. 

CHAPTER  XV 

FRIENDS  AND  ENEMIES  OF  LIVING  ORGANISMS 

Exercise  66.    Bacterial  Cultures. 
Object:     To  show  the  prevalence   of  bacteria  and 
something  of  their  nature. 

Apparatus 

Petri  dishes  Steam  sterilizer 

Culture  media   (gelatine,  agar,         Inoculating  tubes 
and  potato)*  Dissecting  needles 

*Culture  media   ready  for  use  may  be  obtained  from  dealers 
in  laboratory  supplies. 


98  LABORATORY  MANUAL 

Directions:  Thoroughly  wash  all  dishes  and  other 
apparatus  to  be  used  in  this  exercise.  Follow  this  by 
dipping  each  article  separately  into  alcohol.  Then 
place  the  dishes  in  the  steam  sterilizer  and  heat  at  a 
temperature  of  150°  C.  for  a  period  of  twenty  minutes. 
If  gelatin  culture  medium  is  used,  mix  together  the 
following : 


200  c.c.  of  water. 

1  gram  extract  of  beef. 

2  grams  of  peptone. 
20  grams  of  gelatin. 


Place  the  mixture  in  the  dish  in  which  it  is  to  be 
boiled,  heat  until  the  gelatin  is  thoroughly  melted, 
and  then  boil  briskly  for  a  few  minutes.  Test  with 
litmus  paper.  The  solution  should  be  slightly  alkaline. 
If  it  is  not,  add  to  it,  drop  by  drop,  a  solution  of 
sodium  hydroxide  until  it  is  slightly  alkaline  to  litmus 
paper.  Filter  the  solution  through  absorbent  cotton 
and  collect  the  clear  liquid  in  a  sterilized  flask.  Into 
the  sterilized  petri  dishes  pour  enough  of  the  medium 
to  cover  the  bottom  of  the  dish.  Cover  the  dishes 
immediately,  place  them  in  the  sterilizer,  and  heat 
at  a  temperature  of  150°  C.  for  fifteen  minutes.  When 
cooled  sufficiently  to  handle,  set  aside  for  twenty-four 
hours,  then  heat  again  at  150°  C.  for  fifteen  minutes. 
After  another  twenty-four  hours  repeat  the  steriliza- 
tion process.  The  medium  is  now  thoroughly  sterilized 


A  YEAR  IN  SCIENCE  99 

(if  properly  done)  and  is  ready  for  inoculation.  The 
agar  medium  is  prepared  in  the  same  way,  except  that 
instead  of  using  20  grams  of  gelatin,  use  2/5  of  a  gram 
of  agar.  In  all  other  respects  the  culture  is  made  pre- 
cisely as  the  gelatin  culture  medium.  Potato  may  be 
used  by  paring  and  placing  thin  cut  slices  in  the 
sterilized  dishes.  Sterilize  as  indicated  above. 

1.  After    the    medium    has    hardened,    expose    the 
medium  of  one  dish  to  the  air  of  the  laboratory  for 
three  minutes.     Cover  the  dish,  label  it  No.  1,  and  set 
aside  until  the  next  recitation  period. 

2.  At  the  same  time  expose  the  medium  of  another 
dish  to  the  air  out  of  doors  for  three  minutes.     Cover 
and  label  No.  2,  and  set  aside. 

3.  Touch  the  surface  of  the  medium  of  a  third  dish 
with  the  fingers  in  several  places.     Cover,  label  No.  3, 
and  set  aside. 

4.  Over  the  surface  of  the  medium  of  a  fourth  dish, 
roll  the  end  of  your  lead  pencil   (which  you  so  fre- 
quently place   in   your   mouth).     Cover,   label   No.   4, 
and  set  aside. 

5.  If  a  fly  is  obtainable,  capture  it,  and  place  it 
inside   another   dish,   permitting  it  to   walk   over  the 
surface  of  the  medium.     Free  the  fly,  cover  the  dish 
and  label  No.  5.    Set  aside  until  next  recitation. 

(>.  Set  one  dish  aside  unopened  as  a  check,  and  label 
No.  6. 

Place  all  vessels  under  similar  conditions  of  light, 
heat,  etc.  Make  daily  observations  for  the  appearance 


100  LABOBATOBY  MANUAL 

of  colonies  of  bacteria.  Describe  and  sketch  the 
appearance  of  the  growths.  What  do  these  experi- 
ments show  as  to  the  prevalence  of  bacteria  ? 

Exercise  67.    Conditions  for  Bacterial  Growth. 
Object:     To     determine     conditions     for     bacterial 
growth. 

Apparatus 

Hay       .  Test  tubes 

Milk  Absorbent  cotton 

Meat 

Directions :  A.  Prepare  three  test  tubes  as  follows : 
Put  in  one  some  pieces  of  chopped  hay  and  cover  with 
water;  in  the  second  some  milk;  and  in  the  third  a 
small  piece  of  meat  covered  with  water.  Set  these 
aside,  uncovered,  for  a  few  days  and  note  the  changes 
in  appearance  and  odor  of  the  contents.  Mount  some 
of  the  scum  on  a  slide  and  cover  with  a  cover  glass. 
The  instructor  will  find  the  bacteria  for  you  under  the 
high  power  of  the  microscope.  Determine  the  shape 
of  some  of  these  bodies  and  sketch. 

B.  Prepare  three  test  tubes  as  follows:  Fill  each 
tube  half  full  with  milk.  Place  one  in  a  beaker  and 
pack  ice  around  it.  Leave  the  top  open.  Set  the 
entire  apparatus  on  ice  in  the  refrigerator.  Boil  the 
contents  of  the  second  tube  for  a  few  minutes  and 
stopper  with  sterilized  absorbent  cotton.  Set  aside  in 
a  warm  place.  Place  the  third  tube,  uncorked,  in  a 


A  YEAR  IN -SCIENCE  101 

warm  place.  Make  daily  observations  and  'record 
results.  What  is  the  effect  of  heat  on  bacteria?  Of 
cold? 

C.  Prepare  two  test  tubes  as  follows :  Boil  two 
test  tubes  in  water  and  fill  each  half  full  of  boiled 
milk.  Into  one  tube  introduce  some  of  the  scum  from 
the  tube  of  hay  infusion.  Close  the  tube  with  absorbent 
cotton  and  set  in  a  warm  place. 

Take  some  scum  from  the  hay  infusion  and  mix  it 
with  a  teaspoonful  of  a  2%  solution  of  corrosive  sub- 
limate, or  of  formalin,  and  let  it  stand  ten  minutes. 
Then  pour  this  mixture  into  the  second  tube.  Close 
with  absorbent  cotton  and  place  beside  the  first  tube 
in  a  warm  place.  After  a  day  examine  the  contents  of 
the  two  tubes.  Is  the  milk  still  fresh  in  either  tube? 
How  do  you  account  for  the  condition  found? 

From  this  experiment  what  conditions  are  favorable 
to  bacterial  growth?  What  conditions  are  unfavor- 
able? What  are  some  of  the  methods  of  killing 
bacteria? 

Exercise  68.    Root  tubercles. 
Object:    To  show  a  use  of  bacteria. 

Apparatus 

Compound  microscope  Roots  of  legumes 

Slides,  etc. 

Directions:  Bring  to  the  laboratory  the  roots  of 
any  leguminous  plants  (pea,  bean,  vetch,  etc.)  Exam- 
ine the  roots  carefully  for  nodules.  Sketch  to  show 


102  LABORATORY  MANUAL 

their  distribution.  Crush  a  portion  of  a  nodule  on  a 
glass  slide  and  mount  a  portion  of  the  material  in  a 
drop  of  water.  Cover  with  a  cover  glass.  With  the 
aid  of  the  instructor,  find  the  mass  of  moving  bacteria 
under  the  high  power  microscope.  Sketch  to  show  the 
form  of  some  of  the  bacteria.  These  bacteria  are  very 
helpful  to  the  plants  of  the  pulse  family,  enabling 
them  to  obtain  and  utilize  the  nitrogen  from  the  air  as 
food. 

CHAPTER  XVI 

CLASSIFICATION  OF  FOODS 

Substances  which  are  taken  into  the  body  as  nourish- 
ment are  known  as  foods. 

Foods  contain  many  elements,  chief  of  which  are 
carbon,  hydrogen,  oxygen,  nitrogen,  sulphur,  phos- 
phorus, and  iron. 

These  elements  do  not  occur  in  living  matter  as 
elements,  but  in  various  combinations  or  compounds. 
These  compounds  in  foods  are  known  as  foodstuffs. 
There  are  five  such  foodstuffs. 

Proteins,  or  nitrogenous  compounds. 

Carbohydrates,  or  starches  and  sugars. 

Hydrocarbons,  or  fats  and  oils. 

Mineral  salts. 

Water. 


A  YEAR  IN  SCIENCE  103 

Each  foodstuff  shows  certain  definite  qualities  by 
which  its  presence  may  be  detected. 

Exercise  69.    Tests  for  Foodstuffs. 
Object:     To   determine   a  test  for  protein,   starch, 
sugar,  fat  and  oil. 

Apparatus 

Cornstarch  Grape  sugar 

Ammonia  Egg-white 

Benzine  and  ether  Mutton  tallow 

Vnglazed  paper  Ground  flax  seed 

Test  tubes  Iodine 

Evaporating  dish  Fehling's   solution 

Filter  paper  Nitric   acid 

Bunsen  burner  Hydrochloric  acid 
Stirring  rod 

Directions:  A.  Test  for  starch:  Place  a  small 
amount  of  cornstarch  in  a  test  tube.  Add  water  and 
shake  the  mixture.  Does  the  starch  dissolve?  (To 
answer  this  question  compare  this  mixture  with  a 
solution  of  salt  and  water.)  Boil  the  mixture.  What 
hange  do  you  note?  Dip  the  end  of  a  glass  stirring 
rod  into  the  paste.  Over  the  paste  on  the  glass  rod 
pour  a  few  drops  of  iodine.  What  is  the  result? 

B.  Test  for  grape  sugar :  Place  a  small  amount  of 
grape  sugar  in  a  test  tube  and  add  enough  water  to 
dissolve  it.  What  is  the  difference  in  the  effect  of 

at(M-  on  sugar  and  starch?  Add  a  few  drops  of 
Fehling's  solution  and  boil.  What  change  do  you 
To  a  solution  of  cane  sugar  add  Fehling's 


104  LABOEATOEY  MANUAL 

solution  and  boil.  Do  you  obtain  the  same  result? 
Take  a  fresh  solution  of  cane  sugar,  add  a  few  drops 
of  hydrochloric  acid,  then  Fehling's  solution  and  boil. 
How  does  this  result  compare  with  the  two  preceding? 
Thus  cane  sugar  is  converted  into  grape  sugar  by  the 
acid. 

C.  Tests  for  protein :    Into  a  test  tube  half  full  of 
water,  place  some  rav/  egg-white.     Heat  this  over  the 
Bunsen  flame.    What  is  the  effect  of  heat  on  the  egg- 
white  ?    Pour  off  the  water.    Cover  the  egg-white  with 
dilute  nitric  acid  and  boil.     What  is  the  color  of  the 
egg?    Pour  off  the  acid.    Add  enough  ammonia  to  cover 
the  egg.    What  is  the  color  produced? 

D.  Tests  for  oil  and  fat :     To  four  teaspoonfuls  of 
ground  flax  seed,  add  an  equal  volume  of  benzine  or 
ether.     Thoroughly  stir  the  mixture  and  let  it  stand 
for  about  ten  minutes.     Filter  and  place  the  nitrate 
aside  in  a  strong  draught  of  air  until  the  benzine  or 
ether  has  entirely  evaporated.     What  is  the  substance 
left?    What  is  the  odor?    Why  are  benzine  and  ether 
used  to  remove  grease  spots  from  clothing? 

Rub  some  mutton  tallow  on  the  surface  of  a  piece  of 
unglazed  paper.  Hold  the  paper  over  a  Bunsen  flame 
to  melt  the  fat.  Then  hold  it  to  the  light.  What  is 
the  effect  of  fat  or  oil  on  paper?  Summarize  the  tests 
you  have  learned  for  protein,  starch,  sugar,  fat. 

Exercise  70.    Foodstuffs  in  Common  Foods. 

Object:  To  determine  the  foodstuffs  found  in  some 
foods. 


.A  YEAR  IN  SCIENCE 


105 


Egg-white 

Milk 

Potato 

Apple 

Beans    ( soaked ) 

English  walnuts 

Flour 


Apparatus 

Iodine 
Nitric  acid 
Fehling's  solution 
Ammonia 
Unglazed  paper 
Bunsen   burner 


Directions:  Apply  the  four  tests,  which  you  have 
learned  in  Exercise  69,  to  each  of  the  following  foods 
and  tabulate  your  results  as  follows : 


Foods 
Egg-white 
Milk 

Starch 

Grape  Sugar 

Protein 

Oil  and  Fat 

Potato 

Apple 
Beans 

English- 
walnuts 

Flour 

CHAPTER  XVII 

DIGESTIVE  SYSTEM 

Exercise  71.    Study  of  the  Mouth  (home  study). 
Object:     To  study  the  parts  and  structure  of  the 
mouth. 

Apparatus 

Hand  mirror 

Directions:  Take  a  position  with  your  back  toward 
a  strong  light,  and  study  your  mouth  cavity  with  the 
aid  of  a  hand  mirror. 


106  LABORATORY  MANUAL 

A.  Walls  of  the  mouth  cavity. 

1.  How  do  the  walls  enclosing  the  mouth  cavity 
differ  from  each  other  ?    Note  the  hard  portion  or  roof 
of  the  mouth.    How  far  back  does  it  extend?    This  is 
called  the  hard  palate.    The  softer  portion  at  the  back 
of    the    mouth    is    called    the  soft    palate;    hanging 
down  from  its  free  border  is  a  conical  projection,  the 
uvula.     What  is  its  function? 

2.  What   difference   do   you   observe   between   the 
outer  and  inner  covering  of  the   cheeks?     What  are 
the    characteristics   of    the    inner    covering,    or    mucous 
membrane? 

B.  Salivary  glands. 

1.  Pull   aside   with  the   fingers   one   corner   of  the 
mouth.    Find  the  small  elevation  on  the  inside  of  the 
cheek.      The   duct   from    one    of   the    salivary    glands 
(parotid  gland,  lying  close  in  front  of  the  ear)  opens 
on  this  elevation. 

2.  Lift  the  tongue  and  note  the  glands  (sub-lingual) 
lying  just  beneath.    The  ducts  from  these  glands  open 
in  the  front  of  the  mouth  beneath  the  tongue.     Feel 
them  with  the  tip  of  the  tongue. 

3.  Find   the    third   pair    of   salivary    glands    (sub- 
maxillary)    lying  beneath   the  floor   of  the  mouth   just 
behind  the  sub-lingual  near  the  angle  of  the  jaw. 

C.  The  tongue. 

What  kind  of  covering  has  the  tongue?  Describe 
the  difference  between  the  upper  and  under  surfaces. 
Can  you  see  any  difference  in  the  size,  shape,  number, 


A  YEAR  IN  SCIENCE  107 

and   arrangement   of   the   minute    elevations    (papillae) 
on  the  upper  surface? 

D.  The  teeth. 

1.  Teeth  differ  in  minor  points  from  one  another, 
but  in  all,  three  parts  are  found :  one,  seen  in  the  mouth 
and  called  the  crown  of  the  tooth ;  a  second,  imbedded 
in  the  jawbone  and  called  the  root;  and  between  the 
two  surrounded  by  the  edge  of  the  gum,  the  neck  of 
the  tooth. 

2.  Count  the  teeth  in  the  upper  and  lower  jaws. 
How  many  in  all?     Describe  the  edges  of  the  front 
teeth    (incisors).      How    many    teeth    have    this    sharp 
cutting   edge?     How   does   the   tooth    (canine)    next   to 
the  incisors  differ  from  the  other  teeth?     What  is  its 
function?     How  many  teeth  have  two  points  to  the 
crown?     These   are  known   as   bicuspids.     What  is  the 
character  of  the  last  three  teeth?    What  is  their  func- 
tion?    These  are   the  molars.     Do  you  have   all  the 
molars?    Why  not? 

E.  Tonsils. 

The  opening  from  the  back  of  the  mouth  leads  into 
the  throat.  Press  the  tongue  down  and  note  the 
almond  shaped  elevations  at  the  sides  of  the  throat. 
These  are  called  tonsils. 

Exercise  72.  Alimentary  Canal  and  Digestive 
Glands.  (Demonstration.) 

Object:    A  study  of  digestive  organs. 
Apparatus 

Models   of   digestive   organs        Charts 


108  LABOKATOBY  MANUAL 

Directions:  On  the  models  and  charts  locate  the 
parts  of  the  alimentary  canal. 

A.  Alimentary  Canal.     At  the  back  of  the  mouth 
note  the  funnel-shaped  cavity,  the  pharynx  or  throat. 
What  other  openings  are  there  into  this  cavity?  What 
openings  lead  from  this  cavity? 

Note  the  gullet  or  esophagus,  a  small  tube  leading 
from  the  pharynx  to  the  stomach. 

What  is  the  position  of  the  stomach  in  the  body? 
Its  approximate  size  and  shape? 

Following  the  stomach  is  a  long,  very  much  coiled 
tube,  the  small  intestine.  This  tube  connects  with  a 
larger  tube  known  as  the  large  intestine. 

B.  Glands.     The  salivary  glands  of  the  mouth,  the 
parotid,  the  sub-maxillary,  and  the  sub-lingual  were 
studied  in  Exercise  71. 

In  the  internal  walls  of  the  stomach  are  small  glands 
known  &s  gastric  glands.  These  discharge  their  secre- 
tion into  the  stomach. 

Intestinal  glands  are  located  in  the  walls  of  the  first 
part  of  the  small  intestine.  Other  glands  which  pour 
their  secretions  into  the  small  intestine  are  the  pancreas 
and  the  liver. 

The  pancreas  is  a  long,  lobulated  gland  lying 
beneath  the  stomach.  The  liver,  the  largest  gland  in 
the  body,  lies  just  beneath  the  diaphragm  above  and 
to  the  right  of  the  stomach. 

From  the  chart  make  a  drawing  of  the  alimentary 
canal  and  glands,  labeling  parts. 


A  YEAE  IN  SCIENCE  109 

CHAPTER  XVTII 

DIGESTION  AND  ABSORPTION 

Exercise  73.    Digestion  in  the  Mouth. 
Object:     To  determine  the  foodstuffs  acted  upon  by 
saliva. 

Apparatus 

Litmus  paper  Iodine 

Corn  starch  Test  tube 

Egg-white  Test  tube  rack 

Olive  oil  Test  tube  clamp 

Hydrochloric  acid  Bunsen  burner 
Fehling's   solution 

Directions:  Food  is  first  acted  upon  by  a  fluid, 
saliva,  which  is  secreted  by  glands  discharging  into 
the  mouth.  Test  saliva  by  placing  a  piece  each  of  red 
and  blue  litmus  paper  upon  the  tongue.  Is  saliva  acid 
or  base?  Dry  the  mouth  as  much  as  possible  by  swal- 
lowing and  then  place  on  the  top  of  the  tongue  a  pinch 
of  salt.  Can  you  taste  the  salt?  Keep  the  salt  on  the 
tongue  for  a  minute.  What  happens  to  the  salt? 
Can  you  now  taste  it? 

To  determine  the  chemical  action  of  saliva  on  the 
foodstuffs,  prepare  test  tubes  as  follows : 

In  the  first,  place  a  small  amount  of  thin  starch 
paste,  to  which  add  a  few  c.c.  of  saliva.  Label  No.  1. 

In  the  second,  place  some  starch  paste  and  saliva, 
to  which  add  a  few  drops  of  hydrochloric  acid.  Label 
No.  2. 


J10  LABORATORY  MANUAL 

In  the  third,  place  a  few  small  bits  of  egg-white  and 
cover  with  saliva.  Label  No.  3. 

In  the  fourth,  place  a  few  c.c.  of  olive  oil  and  saliva. 
Label  No.  4. 

Shake  the  tubes  and  set  them  in  a  basin  of  water 
having  a  temperature  of  36°  C.,  or  about  body  tem- 
perature. Leave  them  for  half  an  hour  and  then  test 
the  contents  of  the  tubes. 

Tube  No.  1 — Test  part  of  the  contents  for  starch 
and  the  remainder  for  sugar. 

Tube  No.  2 — Repeat  the  test  applied  to  tube  No.  1. 

Tube  No.  3 — Has  the  egg-white  begun  to  dissolve? 

Tube  No.  4 — Has  any  change  taken  place  in  the  oil? 

Upon  which  of  the  foodstuffs  does  saliva  act? 

Does  it  act  in  an  acid  or  base  solution? 

Exercise  74.    Digestion  in  the  Stomach. 
Object:     To  determine  the  foodstuffs  acted  upon  in 
the  stomach. 

Apparatus 

Corn  starch  Test  tube  clamp 

Egg-white  Iodine 

Olive  oil  Sodium  hydroxide    (dilute) 

Milk  Pepsin 

Hydrochloric  acid  (dilute)                Rennet 

Fehling's  solution  Bunsen  burner 

Test  tubes  and  racks 

Directions:  In  the  stomach  the  food  comes  in  con- 
tact with  the  gastric  juice.  This  contains  two  active 
substances,  pepsin  and  rennin. 


A  YEAE  IN  SCIENCE  HI 

A.  Pepsin. 

Make  a  weak  solution  of  pepsin  by  dissolving  a  few 
grams  of  pepsin  in  50  c.c.  of  water. 

Prepare  five  test  tubes  as  follows : 

In  the  first,  place  a  small  amount  of  starch  paste, 
10  c.c.  of  pepsin,  and  a  few  drops  of  very  dilute  hydro- 
chloric acid.  Label  tube  No.  1. 

In  the  second,  place  a  few  pieces  of  egg-white,- 10  c.c. 
of  pepsin,  and  dilute  hydrochloric  acid.  Label  No.  2. 

In  the  third,  place  a  few  pieces  of  egg-white,  10  c.c. 
of  pepsin,  and  a  few  drops  of  very  dilute  sodium 
hydroxide  solution  (0.2%).  Label  No.  3. 

In  the  fourth,  place  5  c.c.  of  olive  oil,  10  c.c.  of  pep- 
sin, and  a  few  c.c.  of  dilute  hydrochloric  acid.  Label 
No.  4. 

Shake  the  tubes  and  keep  them  at  a  temperature  of 
36°  C.  for  24  hours.  At  the  end  of  that  time  test  the 
contents  of  the  tubes. 

Test  No.  1  for  starch  and  sugar. 

In  No.  2,  has  the  egg-white  dissolved? 

In  No.  3,  has  the  egg-white  dissolved? 

In  No.  4,  is  there  any  change  in  the  olive  oil  ? 

Upon  which  foodstuffs  does  pepsin  act? 

In  comparing  tubes  No.  2  and  No.  3  does  pepsin  act 
in  a  base  or  acid  solution? 

B.  Rennin. 

In  the  fifth  tube  place  10  c.c.  of  milk  and  5  c.c.  of 
rennet  (which  contains  rennin).  Set  aside  for  30 


112  LABORATORY  MANUAL 

minutes  at  a  temperature  of  36°  C.    At  the  end  of  that 
time  what  change  do  you  observe  in  the  milk? 

Exercise  75.    Digestion  in  the  Intestine. 
Object:     To  determine  the  foods  acted  upon  by  the 
pancreatic  juice. 

Apparatus 

Corn  starch  Pancreatin 

Egg-white  Bunsen  burner 

Olive  oil  Test  tubes  and  racks 

Hydrochloric   acid  (dilute)  Test  tube  clamps 

Sodium  hydroxide  (dilute) 

Directions:  In  the  small  intestine  the  food  is  acted 
upon  by  three  digestive  juices :  intestinal,  which  is 
secreted  by  the  glands  in  the  walls  of  the  small 
intestine;  bile,  secreted  by  the  liver;  pancreatic, 
secreted  by  the  pancreas. 

Prepare  a  weak  solution  of  pancreatin  by  dissolving 
a  few  grains  of  pancreatin  in  50  c.c.  of  water. 

Prepare  four  test  tubes  as  follows : 

In  No.  1  place  starch  paste,  10  c.c.  of  pancreatin 
solution,  and  a  few  drops  of  very  dilute  sodium 
hydroxide. 

In  No.  2  place  starch  paste,  10  c.c.  pancreatin  solu- 
tion, and  a  few  c.c.  of  hydrochloric  acid. 

In  No.  3  place  a  few  bits  of  egg-white,  pancreatin 
solution,  and  sodium  hydroxide. 

In  No.  4  place  10  c.c.  olive  oil,  pancreatin  solution, 
and  sodium  hydroxide. 


A  YEAR  IN  SCIENCE 


113 


Shake  the  tubes  and  set  them  aside  in  a  temperature 
of  36°  C.  for  24  hours. 

At  the  end  of  that  time  examine : 

No.  1    for  starch   and  sugar. 

No.  2    for  starch  and  sugar. 

No.  3.  Has  the  egg-white  dissolved? 

No.  4.  Has  the  olive  oil  changed? 

Upon  which  foodstuffs  does  pancreatin  act?  Does  it 
act  in  an  acid  or  base  solution?  From  the  last  three 
exercises  complete  the  following  table : 


Digestive 
Fluid 

Acid  or 
Base 

Region  of 
Alimentary         Foodstuffs         Digested 
Canal              Acted  Upon         Product 

Saliva 
Gastric 
Pepsin 
Rennin 
Pancreatin 

Exercise  76.    Absorption. 

Object:     To  determine  which  foodstuffs  will  diffuse 
through  an  animal  membrane. 


Corn  starch 
Olive  oil 
Egg-white  (raw) 
Iodine 
Ammonia 
Nitric  acid 


Apparatus 

Thistle  tube 
Animal  membrane 
Glass  jar 
Ring  stand 
Twine 


Directions:  For  the  method  of  setting  up  the 
apparatus  for  this  exercise,  see  Exercise  5  on  "Diffu- 
sion of  Liquids  through  a  Membrane. ' '  Set  up  similar 
experiments,  using  in  place  of  the  molasses : 


LABORATORY  MANUAL 

a.  starch  paste, 

b.  olive  oil, 

c.  raw  egg-white. 

After  48  hours  note  any  change  in  the  level  of  the 
liquids  in  the  thistle  tubes.  At  the  same  time  test  the 
water  in  which  the  bulbs  of  the  thistle  tubes  were 
suspended : 

a.  for  starch, 

b.  for  oil, 

c.  for  protein. 

Has  diffusion  taken  place  in  any  of  the  foregoing? 
In  Exercise  5  did  molasses  diffuse  through  the  animal 
membrane?  Why  is  it  necessary  to  have  foods 
digested? 

CHAPTER  XIX 

CIRCULATORY  SYSTEM 

Exercise  77.  Study  of  Beef  "Pluck."  (Demon- 
stration.) 

Object:  A  study  of  the  relation  of  the  heart  and 
lungs  and  their  structure. 

Apparatus 

Beef  "pluck,"  to  consist  of  the  Plaster  model 

trachea,  lungs,  heart,  and  its  Scissors 

covering,  and  the  main  blood-  Scalpel 

vessels   leading  to  and   from  Large  glass  tube 
the  heart 

Directions:    A.    In  what  part  of  the  body  are  these 


A  YEAR  IN  SCIENCE  115 

organs  located?  What  is  their  position  to  each  other? 
Notice  the  trachea  with  its  circular  rings  of  cartilage. 
Are  the  rings  entire?  These  are  necessary  to  prevent 
collapse  of  the  tube.  HOAV  far  down  do  these  rings 
continue?  With  a  scalpel  follow  a  branch  of  the 
trachea  into  the  lungs.  How  do  these  branches  end? 
This  large  amount  of  branching  allows  the  air  to  be 
brought  in  contact  with  very  small  blood  vessels, 
through  the  walls  of  which  oxygen  is  absorbed  into  the 
blood. 

B.  Lungs.    How  many  lobes  has  each  lung?    What 
are  their  relative  sizes  ?    Note  the  texture  of  the  lungs. 
By  inserting  a  glass  tube  into  a  branch  of  one  of  the 
bronchi,    force    air    into    the    lung.      What    happens? 
The    lungs     are     the     organs     chiefly     concerned    in 
breathing. 

C.  Heart.    What  is  the  general  shape?    The  cover- 
ing  about    the    heart    is    the   pericardium.      The    heart 
has  four  compartments:  the  upper  two,  the  auricles 
(right  and  left)  ;  the  lower  two,  ventricles    (right  and 
left).     Which   parts   have   the   thickest   walls?     The 
Avails  are  made  of  muscle  with  the  thick-walled  parts 
doing  the  pumping. 

Find  the  blood  vessels,  superior  and  inferior  vena 
cava,  leading  into  the  right  auricle.  Open  the  veins, 
also  the  walls  of  the  auricle,  and  observe  the  path  of 
the  blood  into  the  right  ventricle.  Note  the  tricuspid 
valve  that  closes  this  entrance  between  auricle  and 
ventricle.  Also  notice  the  cords  bv  which  this  valve 


114  LABORATORY  MANUAL 

a.  starch  paste, 

b.  olive  oil, 

c.  raw  egg-white. 

After  48  hours  note  any  change  in  the  level  of  the 
liquids  in  the  thistle  tubes.  At  the  same  time  test  the 
water  in  which  the  bulbs  of  the  thistle  tubes  were 
suspended : 

a.  for  starch, 

b.  for  oil, 

c.  for  protein. 

Has  diffusion  taken  place  in  any  of  the  foregoing? 
In  Exercise  5  did  molasses  diffuse  through  the  animal 
membrane?  Why  is  it  necessary  to  have  foods 
digested? 

CHAPTER  XTX 

CIRCULATORY  SYSTEM 

Exercise  77.  Study  of  Beef  ''Pluck."  (Demon- 
stration.) 

Object:  A  study  of  the  relation  of  the  heart  and 
lungs  and  their  structure. 

Apparatus 

Beef  "pluck,"  to  consist  of  the  Plaster  model 

trachea,  lungs,  heart,  and  its  Scissors 

covering,  and  the  main  blood-  Scalpel 

vessels   leading  to  and   from  Large  glass  tube 
the  heart 

Directions:    A.    In  what  part  of  the  body  are  these 


A  YEAR  IN  SCIENCE  H5 

organs  located?  What  is  their  position  to  each  other? 
Notice  the  trachea  with  its  circular  rings  of  cartilage. 
Are  the  rings  entire?  These  are  necessary  to  prevent 
collapse  of  the  tube.  How  far  down  do  these  rings 
continue?  With  a  scalpel  follow  a  branch  of  the 
trachea  into  the  lungs.  How  do  these  branches  end? 
This  large  amount  of  branching  allows  the  air  to  be 
brought  in  contact  with  very  small  blood  vessels, 
through  the  walls  of  which  oxygen  is  absorbed  into  the 
blood. 

B.  Lungs.    How  many  lobes  has  each  lung?    What 
are  their  relative  sizes  ?    Note  the  texture  of  the  lungs. 
By  inserting  a  glass  tube  into  a  branch  of  one  of  the 
bronchi,    force    air    into    the    lung.      What    happens? 
The    lungs     are     the     organs     chiefly     concerned    in 
breathing. 

C.  Heart.    What  is  the  general  shape?    The  cover- 
ing  about    the    heart    is    the   pericardium.      The    heart 
has  four  compartments:  the  upper  two,  the  auricles 
(right  and  left)  ;  the  lower  two,  ventricles    (right  and 
left).     Which   parts   have   the   thickest   walls?     The 
walls  are  made  of  muscle  with  the  thick-walled  parts 
doing  the  pumping. 

Find  the  blood  vessels,  superior  and  inferior  vena 
cava,  leading  into  the  right  auricle.  Open  the  veins, 
also  the  walls  of  the  auricle,  and  observe  the  path  of 
the  blood  into  the  right  ventricle.  Note  the  tricuspid 
valve  that  closes  this  entrance  between  auricle  and 
ventricle.  Also  notice  the  cords  bv  which  this  valve 


118  LABORATORY  MANUAL 

number?  In  size?  The  smaller  are  called  red  cor- 
puscles. How  are  they  arranged?  Can  you  make  out 
their  shape?  Make  two  drawings  of  a  red  corpuscle, 
one  as  seen  on  end,  the  other  from  the  side. 

The  larger  bodies  are  the  white  corpuscles.  Describe 
them. 

CHAPTER  XX 

RESPIRATORY  SYSTEM 

Exercise  79.  Respiratory  Organs  and  Mechanics  of 
Respiration.  (Demonstration.) 

Object:  To  study  the  organs  and  mechanics  of 
respiration.  . 

Apparatus 

Chart  or  plaster  model  Sheet  rubber 

Skeleton  Rubber  balloon 

Mechanical  device  for  rib  action  Glass  tube 
Belljar  with  stopper 

Directions:  A.  The  lungs  are  the  chief  organs  of 
respiration.  The  structure  of  the  lungs  was  studied 
in  Exercise  77,  in  the  study  of  the  beef  "pluck."  Note 
on  the  chart  or  plaster  model  their  position  in  the 
body.  The  cavity  in  which  the  lungs  and  heart  are 
found  is  the  thorax.  On  the  skeleton  note  the  bones 
forming  the  frame  work  of  this  cavity.  The  floor  of 
the  thorax  is  a  muscular  sheet  called  the  diaphragm. 
Note  on  the  skeleton  the  attachment  of  the  ribs  to  the 
sternum  by  means  of  cartilage.  This  permits  the 


A  YEAK  IN  SCIENCE 


119 


movement   of  the   ribs  by   the   action   of  the   muscles 
between  the  ribs  called  the  intercostals. 

To  demonstrate  this  movement  use  the  mechanical 

device. 


in 


The  vertical  bar  AB  represents  the  spinal  column, 
DF  the  sternum,  CD  and  EF  two  ribs.  Letter  c  repre- 
sents the  muscular  attachment  from  the  spine  and 
collar  bone  to  the  ribs.  Letters  a  and  b  represent  inter- 
costal muscles. 

Note  on  the  skeleton  that  the  ribs  slant  downward 
toward  the  sternum.  On  the  device  place  the  bar  DF 
lower  than  points  CE.  Measure  the  perpendicular  dis- 
tance between  CE  and  DF.  Then  lift  the  ribs  CD  and 
EF  to  a  position  perpendicular  to  AB  (in  the  body  this 
movement  is  brought  about  by  the  contraction  of  the 
intercostal  muscles).  Again  measure  the  perpendicular 
distance  between  CE  and  DF.  How  does  it  compare 
with  the  first  measurement?  How  has  the  position  of 
DF  been  affected?  How  does  this  movement  affect  the 
size  of  the  thoracic  cavity? 

B.     The  thoracic  cavity  is  enlarged  vertically  by  the 


120 


LABOEATOEY  MANUAL 


movements  of  the  diaphragm.     This  action  is  demon- 
strated by  the  following  experiment : 

Fasten  a  toy  balloon  to  one 
end  of  a  glass  tube.  Insert  the 
tube  into  a  rubber  stopper  and 
fit  this  into  the  bell  jar  with  the 
balloon  suspended  inside.  Over 
the  other  end  of  the  belljar, 
securely  fasten  the  rubber  sheet 
to  the  center  of  which  a  handle 
has  been  attached.  The  belljar 
represents  the  chest  walls,  the 
tube  the  trachea,  and  the  bal- 
loon a  lung.  The  rubber  sheet  represents  the 
diaphragm. 

Pull  the  rubber  sheet  downward.  What  happens  to 
the  balloon?  Then  let  the  rubber  sheet  return  to  its 
normal  position.  What  is  the  effect  on  the  balloon? 
The  action  of  the  balloon  represents  the  action  of  the 
lungs  in  response  to  the  movements  of  the  diaphragm. 

Exercise  80.  Comparison  of  Expired  and  Inspired 
Air. 

Object:  To  determine  the  changes  which  take  place 
in  the  air  while  in  the  lungs. 

Apparatus 


Thermometer 

Glass  plate 

Wide  mouth  bottles 

Two-holed  rubber  stopper 


Glass  tubing 
Lime  water 
Pine  splinter 
Pneumatic  trough 


A  YEAR  IN  SCIENCE  121 

Directions:  A.  Temperature.  Expose  the  ther- 
mometer to  the  room  temperature  for  five  minutes 
and  record  the  temperature.  Then  breathe  on  the  bulb 
of  the  thermometer  for  a  few  minutes  and  record  the 
temperature  of  expired  air.  What  change  has  taken 
place  in  the  temperature  of  the  air  while  in  the  lungs  ? 

B.  Composition.  For  the  composition  of  inspired 
air  see  Exercise  38. 

a.  Breathe  on  the  glass  plate.    What  collects  on  the 
surface?    Does  expired  air  contain  more  or  less  mois- 
ture than  inspired  air  ? 

b.  Into  a  wide  mouth  bottle  pour  lime  water  to 
the  depth  of  an  inch.    Fit  the  mouth  of  the  bottle  with 
a  rubber  stopper  fitted  with  a  long  and  short  glass 
tube.    Adjust  the  long  tube  so  that  the  end  is  below 
the  level  of  the  lime  water.     Draw  air 

from  the  room  through  the  lime  water  by 
suction  applied  to  the  free  end  of  the 
short  tube.  Continue  this  for  two  minutes. 
Insert  the  stopper  with  the  tubes  into  a 
second  bottle  containing  lime  water.  Pass 
expired  air  through  the  lime  water  by 


blowing  into  the  free   end   of  the  long        Fig-  32- 
tube.     Continue  this  for.  two  minutes.     How  does  the 
lime  water  in  the  two  bottles  compare?    Which  contains 
the  greater  amount  of  carbon  dioxide,  inspired  or  expired 
air? 

c,     Fill    a    bottle   Avith    expired    air   by   downward 
displacement  of  water.    Turn  the  bottle  mouth  upward 


122  LABOEATOKY  MANUAL 

and  introduce  into  it  a  burning  splinter.  Does  the 
splinter  continue  to  burn  as  brightly  as  in  the  air? 
What  does  this  indicate? 

Air  expired  in  ordinary  breathing  has  lost  about 
one-fourth  of  the  oxygen  contained  in  inspired  air. 

Exercise  81.    School  Ventilation. 
Object:     To   determine  the  efficiency   of  the  room 
ventilation. 

Apparatus 

Tape  measure 

Directions:  For  a  sufficient  air  supply  most  author- 
ities agree  that  an  individual  requires  300  cu.  ft.  of 
space  with  1,800  cu.  ft.  of  air  per  hour. 

With  the  tape  measure  determine  the  dimensions  of 
the  laboratory.  From  the  dimensions  what  is  the 
volume  of  the  laboratory  in  cubic  feet? 

Divide  the  cubic  contents  of  the  laboratory  by  the 
number  of  people  in  the  room.  How  does  the  quotient 
compare  with  the  number  of  cubic  feet  of  space  each 
individual  should  have? 

What  is  the  method  of  ventilation  in  the  school 
building?  Learn  from  those  in  authority  the  number 
of  times  per  hour  the  air  is  changed  in  the  room. 
Compute  from  this  data  the  number  of  cubic  feet  of 
air  each  person  receives  per  hour.  Is  this  sufficient  for 
the  individual? 

Follow  the  same  directions  in  computing  the  volume 
of  your  session  room.  Divide  the  cubic  contents  by 


A  YEAK  IN  SCIENCE  123 

the  number  of  students  in  the  room.  Determine  the 
number  of  cubic  feet  of  air  each  individual  receives  per 
hour.  Has  each  individual  the  requisite  amount  of 
air?  If  not,  what  change  would  you  suggest  to  meet 
the  requirements? 

For  your  own  information  compute  the  volume  of 
your  sleeping  room  in  cubic  feet.  How  long  would 
the  air  in  the  room  suffice  without  change?  What 
means  are  there  for  changing  the  air  in  the  room? 
Are  these  sufficient?  From  what  you  have  learned 
above,  correct  the  fault. 

CHAPTER  XXI 
EXCRETORY  SYSTEM 

Exercise  82.    The  Kidneys. 

Object:     To  study  the  structure  of  a  kidney. 

Apparatus 

Sheep  kidney  Scalpel 

Dissecting  pan  Scissors 

Directions:  Describe  the  capsule  surrounding  the 
kidney.  Where  is  it  attached  to  the  kidney?  Slit  the 
capsule  on  the  convex  side  enough  to  allow  the  kidney 
to  be  removed.  Cut  the  kidney  longitudinally  from 
the  convex  border  toward  the  hilum  sufficiently  to  open 
the  cavity  within. 

What  is  the  shape  of  the  kidney  ?  Size  ?  Color  ?  How 
many  tubes  do  you  find  connected  with  this  organ? 
In  the  longitudinal  section  of  the  kidney  notice  two 


124  LABORATORY  MANUAL 

parts:  the  outer  solid  part,  the  cortex;  the  inner 
striated  part,  the  medulla.  The  slight  elevations  are 
called  pyramids  of  Malpiglii,  between  which  small 
tubes  may  be  seen  leading  into  the  sinus.  The  tube 
leading  from  the  sinus  is  the  ureter  which  carries  the 
excretion  into  the  bladder.  Notice  the  enlarged  end 
of  the  ureter  in  the  sinus.  Note  also  the  entrance  of 
the  renal  artery  and  the  renal  vein  into  the  kidney 
just  above  the  ureter.  The  artery  brings  in  the  blood 
which  gives  up  its  waste  in  the  kidney.  This  waste  is 
collected  by  the  tubules  and  emptied  from  the  sinus 
into  the  ureter.  The  capillaries  collect  the  blood  which 
has  been  cleared  of  waste  and  return  it  to  the  vein. 

Exercise  83.    The  Skin. 

Object:  To  study  the  structure  and  functions  of  the 
skin. 

Apparatus 

Plaster  model  of  skin 

Directions :  A.  External  structure :  The  outer 
layer  of  the  skin  is  called  the  cuticle,  .or  the  epidermis. 
What  is  its  color  ?  Thickness  ?  Where  is  it  thickest  on 
the  hand?  What  markings  do  you  find  on  it?  Can 
you  find  the  pores,  openings  of  the  sweat  glands  ?  Does 
the  epidermis  contain  blood  vessels?  Does  it  contain 
nerves  ? 

B.  Internal  structure :  From  the  plaster  model,  or 
a  prepared  slide  of  the  skin,  note  the  two  layers 
comprising  it.  Note  the  epidermis  again.  What  is  its 


A  YEAE  IN  SCIENCE  125 

structure?  The  inner  layer  is  the  derm-is.  How  does 
it  compare  with  the  epidermis  in  thickness?  Note 
that  its  surface  is  ridged.  These  ridges  are  made  up 
of  a  number  of  papillae.  Each  papilla  marks-  the  end 
of  a  nerve  of  touch.  Is  the  skin  sensitive  to  other 
stimuli  than  touch?  If  so,  what  are  they?  In  the 
dermis  locate  the  fat  cells,  the  roots  of  the  hair,  the 
oil  or  sebaceous  glands,  and  the  sic  eat  glands.  Where 
do  the  ducts  from  the  sweat  glands  open  ?  What  effect 
does  the  evaporation  of  sweat  from  the  surface  of  the 
skin  have  on  the  temperature  of  the  skin?  To  answer 
this  question  refer  to  Exercise  21. 

Make  a  drawing  to  show  the  parts  of  the  skin. 

From  this  exercise  what  are  some  of  the  functions 
of  the  skin? 

Hair  and  nails  are  modifications  of  the  skin. 

CHAPTER  XXII 
SKELETAL  SYSTEM 

Exercise  84.    The  Skeleton. 

Object:     To  study  the  general  plan  of  the  skeleton. 

Apparatus 

Skeleton 

Directions:  The  skeleton  may  be  divided  into  three 
parts :  the  head,  trunk,  and  limbs  with  the  bones  to 
which  they  are  attached,  hip  and  shoulder. 

A.     Head.    Notice  that  the  head  is  divided  into  the 


LABOEATOEY  MANUAL 

face  and  the  cranium.  The  face  is  composed  of  a  num- 
ber of  irregular  bones.  The  cranium  consists  of  a 
number  of  flat  bones,  sutured  together  to  form  a  strong 
covering  for  the  brain. 

B.  Trunk.    The  trunk  consists  of  the  spinal  column, 
breast-bone,  and  ribs. 

The  spinal  column  is  composed  of  a  number  of 
irregular  bones  called  vertebrae.  The  upper  seven 
are  the  neck,  or  cervical  vertebrae.  The  next  twelve 
to  which  the  ribs  are  attached  are  the  dorsal  vertebrae. 
The  five  following  are  the  lumbar  vertebrae.  The  next 
five  in  the  adult  are  grown  together,  forming  the 
sacrum.  This  is  followed  by  four  small  vertebrae  united 
to  form  the  coccyx. 

How  do  the  lower  vertebrae  compare  in  size  with 
the  upper?  What  are  the  advantages  of  this  arrange- 
ment ? 

Note  the  pads  of  cartilage  between  the  vertebrae. 
What  is  their  purpose?  Through  the  center  of  this 
chain  of  bones  is  a  canal  which  contains  the  spinal 
cord.  How  many  curves  in  the  backbone  ?  Of  what 
advantage  are  the  curves?  Note  the  flat  breast-bone. 
Of  how  many  bones  is  it  composed?  What  bones  are 
attached  to  it? 

How  many  ribs  are  there  ?  Where  are  they  attached  ? 
How  many  have  one  end  free?  What  is  their  general 
shape  ? 

C.  Limbs.     The  shoulder  consists   of  the  shoulder 
blade  and  collar  bone.     Locate  these.     Note  the  socket 


A  YEAE  IN  SCIENCE  127 

formed  by  their  union  for  the  upper  limb.  The  upper 
limb  consists  of  the  upper  arm  bone,  the  humerus;  two 
bones  in  the  forearm,  the  ulna  and  radius;  eight  irregu- 
lar wrist  bones,  the  carpals;  five  bones  in  the  palm  of 
the  hand,  the  metacarpals;  and  fourteen  bones  in  the 
fingers,  the  phalanges. 

The  hip  consists  of  one  large  bone  on  each  side. 
Notice  the  size  and  strength  of  the  hip  as  compared 
with  the  shoulder.  Why  this  difference  ? 

The  lower  limb  consists  of  the  upper  leg  bone,  the 
femur;  the  two  lower  leg  bones,  the  tibia  and  fibula;  the 
knee  cap  or  patella;  seven  ankle  or  tar  sal  bones;  five 
metatarsals;  and  fourteen  toe  bones  or  phalanges. 

Compare  each  of  these  parts  with  the  corresponding 
parts  in  the  arm. 

Exercise  85.    Structure  and  Composition  of  Bone. 
Object:     To  study  the  structure  and  chemical  com- 
position of  bone. 

Apparatus 

Section  of  a  long  bone  Hydrochloric  acid  20% 

(femur)  Glass  cylinder 

Beef  rib 

Directions:  A.  Structure.  Examine  a  long  bone. 
Note  the  long  central  shaft  with  enlarged  ends.  Of 
what  advantage  are  the  enlarged  ends  ?  Note  the  pink- 
ish colored  covering  surrounding  the  bone.  What  is 
its  function?  This  covering  is  the  periosteum.  Make 
a  longitudinal  section  through  the  bone.  Beneath  the 
periosteum  note  the  hard  bone;  inside  of  this  the  spongy 


128  LABORATORY  MANUAL 

bone  and  central  canal.  The  spongy  bone  contains  in 
its  cavities  red  marrow,  while  the  central  canal  contains 
yellow  marrow. 

B.  Composition.  To  determine  the  chemical  compo- 
sition of  bone,  place  a  rib  in  a  twenty  per  cent  solu- 
tion of  hydrochloric  acid.  Leave  the  bone  in  the  solu- 
tion for  at  least  four  days.  At  the  end  of  that  time 
examine  the  bone.  Has  it  changed  in  shape?  Can  it 
be  cut  ?  Is  it  elastic  ?  The  acid  has  dissolved  from  the 
bone  the  mineral  matter  leaving  only  the  animal  mat- 
ter,  cartilage.  The  animal  matter  may  be  extracted  by 
burning  the  bone.  Again  the  shape  remains  the  same 
but  the  substance  left  is  hard  and  brittle.  This  mineral 
matter  is  chiefly  lime. 

CHAPTER  XXIII 

MUSCULAR  SYSTEM. 

Exercise  86.    Levers. 

Object:  To  determine  the  action  and  advantages  of 
levers. 

Apparatus 

Yard  stick  Ring  stand 

Weight   (500  gms.)  Lever  holders 

Spring  balance 

Directions:  A  lever  is  an  inflexible  bar  moving 
about  a  fixed  point,  called  a  fulcrum,  and  having  two 
other  points,  called  power  and  weight.  Weight  is  the 


A  YEAE  IN  SCIENCE 


129 


mass  moved.  Power  is  the  force  used  to  move  the 
mass.  Weight  arm  (W.  A.)  is  the  distance  from  the 
fulcrum  to  the  point  of  application  of  the  weight. 


Fig.   33. 

Power  arm  (P.  A.)  is  the  distance  from  the  fulcrum 
to  the  point  of  application  of  the  power. 

Levers  are  divided  into  three  classes  based  upon 
the  relative  positions  of  the  three  points :  fulcrum, 
power,  and  weight. 

In  the  first  class  lever,  the  fulcrum  is  in  the  middle, 
the  weight  at  one  end,  and  the  power  at  the  other. 

The  second  class  lever  has  the  fulcrum  at  one  end, 
the  power  at  the  other  end,  and  the  weight  in  the 
middle. 

The  third  class  lever  has  the  fulcrum  at  one  end,  the 
weight  at  the  other  end,  and  the  power  in  the  middle. 

Fasten  one  end  of  the  yard  stick  to  the  ring  stand. 
From  the  second  ring  stand  suspend  the  spring  bal- 
ance. Wire  the  free  end  of  the  yard  stick  to  the  hook 
of  the  spring  balance.  Take  the  reading  of  the 
indicator  on  the  scale.  Suspend  the  500  gm.  weight 
from  the  zero  point  on  the  yard  stick. 


130 


LABOKATORY  MANUAL 


Locate  on  the  apparatus  the  fulcrum,  the  power, 
weight,  power-arm,  and  weight  arm. 

Shift  the  weight  on  the  bar,  and  record  the  readings 
on  the  balance  with  the  weight  at  0,  6,  12,  18,  24,  30, 
and  36  inches  from  the  fulcrum. 

Tabulate  your  readings  as  follows : 


Power  X  Power-arm  = 

Product 

Weight  X  Power-arm  = 

Product 

How  do  the  two  product  columns  compare?  What 
class  of  lever  is  used  in  this  exercise? 

Of  what  mechanical  advantage  is  the  lever  in  lifting 
the  500  gm.  weight  as  shown  by  the  reading  at  the 
6-inch  point? 

How  would  you  convert  this  apparatus  into  a  third 
class  lever?  Into  a  first  class  lever? 

From  the  results  of  this  exercise  what  law  can  you 
deduce  for  levers? 

Exercise  87.    Muscles.     (Demonstration.) 
Object:     To  determine  the  structure  and  action  of 
muscles. 


Frog 

Dissecting  pan 
Scalpel 


Apparatus 

Scissors 
Needles 


A  YEAR  IN  SCIENCE  131 

Directions;  Dissect  away  the  skin  of  a  frog's  leg. 
Note  the  muscles  on  the  leg.  What  is  the  general  shape 
of  the  muscle?  Note  the  tendon  attachment  of  the 
muscles  to  the  bone.  Of  Avhat  advantage  is  the  tendon 
attachment?  Note  that  the  body  of  the  muscle  is  sur- 
rounded by  a  thin  sheet  of  connective  tissue.  Find 
the  large  muscle  on  the  calf  of  the  leg.  Where  are  its 
two  ends  attached?  What  effect  does  the  contraction 
of  this  muscle  have  upon  the  lower  leg?  Upon  the 
foot?  The  bones  of  the  skeleton  serve  as  places  for 
muscle  attachment  and  as  levers  for  their  action. 

CHAPTER  XXIV 

NERVOUS  SYSTEM 

Exercise  88.    Nervous  System.     (Demonstration.) 
Object:    To  study  the  brain,  spinal  cord,  and  nerves. 

Apparatus 

Perch  Scalpel 

Dissecting  pan  Model  of  human  brain 

Scissors 

Directions:  Carefully  dissect  away  the  roof  of  the 
cranium  and  the  dorsal  part  of  the  spinal  column  of 
the  fish  to  expose  the  brain  and  the  spinal  cord.  Note 
that  the  brain  is  divided  into  a  number  of  regions :  the 
small  anterior  lobes,  the  olfactory  lobes;  the  larger 
cerebral  hemispheres;  the  rounded  optic  lobes;  the 
single  lobed  cerebellum;  and  behind  this,  tapering  grad- 
ually into  the  spinal  cord,  the  medulla  oblongata. 


132  LABORATORY  MANUAL 

From  these  centers  branches  lead  to  all  parts  of  the 
head  and  to  some  of  the  internal  organs. 

Examine  the  spinal  cord  in  the  fish.  Is  it  of  the 
same  dimensions  throughout  its  length?  Note  the 
numerous  lateral  branches.  Are  they  single  or  in 
pairs?  These  are  distributed  to  the  remaining  parts 
of  the  body. 

Examine  the  model  of  the  human  brain.  Observing 
the  upper  surface  of  the  brain,  note  the  two  large  con- 
voluted (folded)  hemispheres  of  the  fore-brain,  or 
cerebrum.  At  the  base  of  the  cerebrum  note  the 
smaller  lobes  of  the  cerebellum.  How  do  the  convolu- 
tions on  the  cerebellum  compare  in  size  with  those  of 
the  cerebrum  ?  What  is  the  color  of  each  ? 

On  the  under  surface  of  the  brain,  note  again  the 
cerebral  hemispheres  and  the  cerebellum.  How  do 
they  compare  in  size?  At  the  forward  end  of  the 
cerebrum  note  the  two  small  white  olfactory  lobes. 
Back  of  these  note  the  two  nerves  which  cross.  These 
are  the  optic  nerv&s.  The  third  portion  of  the  brain 
is  the  medulla  oblongata.  On  the  model  it  is  the  white 
portion  lying  just  beneath  and  in  front  of  the  cere- 
bellum. Extending  downward  from  the  medulla  is  the 
spinal  cord  which  continues  through  the  spinal  column. 

Nerves  are  given  off  in  pairs  from  the  brain  and 
spwwl  cord  which  continues  through  the  spinal  column. 

On  the  model  of  the  longitudinal  section  of  the  brain, 
locate  the  parts  mentioned  above. 


A  YEAR  IN  SCIENCE  133 

CHAPTER  XXV 
ORGANS  OF  SPECIAL  SENSES 

Exercise  89,    Cutaneous  Sensations. 
Object:     A  study  of  the  sensations   of  touch  and 
temperature. 

Apparatus 

Metal  compasses  Cold  water 

Hot  water 

Directions:  A.  One  pupil  should  operate,  another 
acting  as  subject.  The  subject  should  be  blindfolded. 
What  is  the  least  distance  apart  at  which  the  two 
points  of  the  compass  may  be  held  and  felt  as  two 
points,  when  applied  to  the  tips  of  the  fingers  ?  The  tip 
of  the  tongue?  Back  of  the  hand?  Back  of  the  neck? 
Record  results.  Are  all  parts  of  the  body  equally 
sensitive  to  touch?  Which  parts  are  most  sensitive? 

B.  Dip  a  point  of  the  compass  in  cold  water  and 
move  it  lightly  over  the  back  of  the  hand.  Does  it 
feel  equally  cold  to  all  parts  of  the  hand?  Mark  with 
an  ink  dot  those  spots  where  the  sensation  is  most 
acute.  Now  dip  the  compass  point  in  hot  water,  and 
repeat  the  experiment.  Locate  as  before,  the  points 
where  the  sensation  is  most  .acute.  Do  the  hot  and 
cold  spots  coincide?  Test  other  areas  of  the  body  in 
the  same  way.  Are  all  parts  of  the  body  equally 
sensitive  to  temperature  ?  Which  parts  are  most  sensi- 


134  LABOEATOEY  MANUAL 

tive?    Least  sensitive?    Where  are  the  hot  spots  most 

numerous?    Where  are  the  cold  spots  most  numerous? 

C.     Do  we  derive  any  sensations  other  than  touch  and 

temperature  through  the  skin?    If  so,  what  are  they? 

Exercise  90.    Organs  of  Taste  and  Smell. 
Object:    A  study  of  the  tongue  and  the  sensations  of 
taste  and  smell. 

Apparatus 

Sugar  Quinine 

Salt  Onion 

Vinegar 

Directions:  A.  With  the  aid  of  a  mirror  examine 
the  upper  and  lower  surfaces  of  the  tongue.  What 
differences  do  you  note?  The  raised  points  on  the 
upper  surface  are  called  papillae.  Observe  that  they 
are  of  three  forms :  long  and  slender,  filiform;  small, 
red,  mushroom  shaped  spots,  fungi  form;  far  back 
on  the  tongue  the  large  circumvallate  papillae.  How 
many  of  them  can  you  see?  Draw  an  outline  of  the 
tongue,  and  locate  on  it  the  regions  where  these  dif- 
ferent forms  are  to  be  found. 

B.  Place  some  sugar  on  the  tip  of  the  tongue.    Let 
it  dissolve.     Has  it  any  taste?     Repeat,  placing  the 
sugar  at  the  back  of  the  tongue.    Is  its  sweetness  more 
or    less    prominent?      Repeat    again,    using    quinine, 
vinegar,  and  salt  successively.     Where  are  the  sensa- 
tions of  bitterness,  sourness,  sweetness,  and  saltiness 
most  prominent? 

C.  The  sense   organs  of  smell  are  located  in  the 


A  YEAR  IN  SCIENCE  135 

mucous  membrane  lining  the  upper  part  of  the  cavity 
of  the  nose.  Particles  of  matter  in  the  form  of  a  gas 
striking  this  membrane  stimulate  the  nerves  of  smell, 
olfactory  nerves.  To  determine  which  of  the  sub- 
stances named  under  "Apparatus"  have  taste  and 
Avhich  have  odor,  perform  the  following  experiment. 
Place  each  of  these  substances  011  the  tongue  of  a 
pupil  who  has  been  previously  blindfolded,  and  who  is 
holding  his  nose  tightly.  Record  the  substance  recog- 
nized by  taste  alone.  Repeat,  leaving  the  nose  free. 
Record  the  substances  recognized  by  smell  alone;  by 
taste  and  smell  combined. 

Exercise  91.    Organ  of  Sight. 

Object:  To  study  the  structure  and  action  of  the 
eye. 

Apparatus 

Model  of  human  eye  Lenses 

Directions:  A.  With  the  aid  of  a  mirror  examine 
the  eye.  Feel  the  upper  eyelid;  fold  it.  In  what  part 
of  it  is  there  a  stiff,  thick  strip  of  connective  tissue? 
Compare  with  this  the  corresponding  strip  in  the 
lower  lid.  At  the  angle  of  the  lower  lid,  about  one- 
eighth  of  an  inch  from  the  inner  corner,  look  for  a 
little  papilla  in  which  is  the  opening  of  the  tear  duct. 
Can  you  find  a  similar  opening  in  the  upper  lid? 
Notice  the  eyeball.  What  do  you  find  in  the  inner 
corner  which  is  different  from  the  outer?  The  eye 


136  LABORATORY  MANUAL 

is  covered  with  a  firm  white  coat,  the  sclerotic,  except 
in  front  wrhere  there  is  a  clear  layer,  the  cornea.  Look 
at  your  neighbor's  eye  from  the  side.  Does  the  cornea 
curve  more  or  less  than  the  remainder  of  the  eye? 
Directly  back  of  the  cornea  is  the  colored  part  of  the 
eye,  called  the  iris.  In  the  center  of  the  iris  is  a  hole, 
the  pupil.  Compare  the  size  of  the  pupil  when  in  a 
bright  light  with  its  size  in  a  dim  light.  From  this, 
what  do  you  conclude  is  the  function  of  the  iris?  Is 
its  action  voluntary  or  involuntary? 

Now  examine  the  model.  Locate  the  parts  mentioned 
above.  The  wall  of  the  eyeball  consists  of  three 
layers :  the  outer,  composed  of  the  sclerotic  and  the 
cornea;  the  middle,  the  black  choroid,  and  in  front 
the  colored  iris;  and  the  inner,  the  retina.  Note  where 
the  optic  nerve  enters  the  two  outer  coats  and  spreads 
out  to  form  the  retina.  Just  back  of  the  pupil  note 
the  convex  crystalline  lens.  The  space  between  the 
lens  and  the  cornea  is  filled  with  a  liquid,  the  aqueous 
humor;  and  the  larger  space  back  of  the  lens  is  filled 
with  a  jelly-like  mass,  the  vitreous  humor.  Draw  a 
section  of  the  eye,  showing  parts  given  above. 

On  the  outside  of  the  model  locate  the  six  muscles 
used  in  moving  the  eyeball.  From  the  position  of  each 
determine  what  motions  it  gives  to  the  eyeball. 

B.  Hold  your  pencil  point  at  several  different  dis- 
tances from  your  eye.  At  what  distance  can  you  see 
it  most  comfortably  and  most  clearly?  From  this 
distance  move  the  pencil  toward  the  eye.  At  what 


A  YEAE  IN  SCIENCE  137 

distance  from  the  eye  does  it  become  indistinct,  or 
fringed  with  a  haze? 

Hold  a  book  with  the  edge  placed  directly  toward 
you.  Close  the  left  eye  and  look  at  the  book.  Then 
close  the  right  eye  and  look  at  it  again.  Then  look 
at  it  with  both  eyes  open.  What  differences  do  you 
note  ?  How  do  you  account  for  these  differences  ? 

In  front  of  a  lens,  both  of  whose  faces  are  convex, 
place  a  lighted  candle  or  a  gas  flame.  Back  of  the 
lens  place  a  piece  of  paper  to  form  a  screen.  Move 
the  paper  back  and  forth  until  a  distinct  image  of  the 
flame  is  seen  upon  the  paper.  What  effect  does  it 
have  upon  the  image  formed  to  move  the  flame  nearer, 
or  farther  away  from  the  lens? 

Adjust  the  apparatus  again  so  that  a  distinct  image 
is  formed  on  the  screen.  Remove  the  lens  and  put 
in  its  place  one  which  is  more  convex.  Which  way 
must  the  screen  be  moved  to  secure  a  distinct  image? 
Repeat  this  experiment,  using  a  lens  which  is  less  con- 
vex than  the  first  one  used;  also  use  one  which  is 
concave. 

Exercise  92.    Organ  of  Hearing. 
Object:    A  study  of  the  ear. 

Apparatus 

Model  of  the  ear 

Directions:  The  ear  is  made  up  of  an  external  ear, 
a  middle  ear,  and  an  inner  ear.  On  the  model  examine 
the  external  ear.  Note  the  pinna,  the  oval,  expanded, 


138  LABORATORY  MANUAL 

funnel-shaped  portion.  Leading  from  this  is  a  canal. 
Across  the  inner  end  of  this  canal,  or  tube,  is  stretched 
a  thin  membrane,  known  as  the  ear  drum  or  tympanic 
membrane.  Examine  the  middle  ear.  What  is  its  size? 
How  is  it  connected  with  the  pharynx?  What  is  the 
name  of  this  tube?  What  is  its  function?  On  the 
inner  surface  of  the  cavity  of  the  middle  ear  and 
separating  it  from  the  inner  ear  are  two  small  open- 
ings covered  with  membrane.  Across  the  cavity  of  the 
middle  ear  is  a  chain  of  three  smaH  bones,  called  from 
their  shape  the  hammer  (malleus),  the  anvil  (incus), 
and  the  stirrup  (stapes)  bones.  How  are  they  placed 
with  reference  to  each  other?  With  reference  to  the 
outer  and  inner  ears?  Can  you  suggest  any  functions 
for  them?  The  inner  ear  is  formed  by  an  irregular 
cavity  in  the  temporal  bone,  and  is  called  the  bony 
labyrinth.  It  is  lined  with  a  membrane  which  secretes 
a  fluid.  It  is  divided  into  three  parts.  The  middle 
part  is  the  vestibule.  The  part  back  of  this  consists 
of  three  tubes,  the  semi-circular  canals.  The  part  in 
front  of  the  vestibule  is  a  single  tube  coiled  like  a 
snail  shell  and  called  the  cochlea.  The  branches  of 
the  auditory  nerve  enter  this  bony  labyrinth.  Locate 
the  parts  of  the  inner  ear  on  the  model.  Draw  a 
diagram  showing  the  relation  of  the  parts  in  the  ear. 


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